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ONBOARD DIAGNOSTIC (OBDII) SYSTEMS

Rob Klausmeier Betsy Dorries October 2005 1

COURSE OUTLINE

•

Overview of OBDII

–

Getting Vehicles “Ready”

–

Key Features of OBDII

–

Results of OBDII tests in I/M Programs

–

Future OBD Requirements

Overview of OBDII Systems

• OBD IS NOT NEW! It was invented by automakers in the early 80s to help diagnose computer controlled engine systems.

• While being a promising concept, early OBD systems had major limitations. • OBDII regulations were developed to maximize the benefits of onboard diagnostic systems.

Overview of OBDII Systems

• The federal government established regulations that required all vehicles to meet specific and consistent requirements for a second generation of onboard diagnostics; this is termed OBDII. • This second generation OBD system was phased in starting in model year 1994. By the 1996 model year, all light-duty vehicles, and by 2004 all medium-duty vehicles sold in the United States had to meet OBDII standards. • The primary purpose of OBDII is to insure that vehicles emit the minimum amount of pollutants through their useful life.

Features of OBDII Systems

• Standardized protocols for communicating with scan tools through a standardized data link connector (DLC) located in an easily accessible location • Determination and recording of readiness status of emission control system monitors • Standardized requirements for illumination of the malfunction indicator lamp (MIL) • Standardized diagnostic trouble codes (DTCs) • Freeze frame 5

Standardized Data Link Connector (DLC)

• OBDII regulations require that manufacturers use a standardized diagnostic connector. This is to allow a generic scan tool to be used on all OBDII equipped systems.

• The connectors for early OBD systems were not standardized. Technicians need a wide variety of interfaces to properly connect to early OBD systems on different vehicles.

• The newly designed diagnostic connector for OBDII, officially known as the DLC, contains 16 terminals. Seven of these are OBDII specific, while the remaining nine are reserved for the discretionary purposes of the manufacturer. 6

Standardized Communication Protocol

• • • OBDII regulations have required that manufacturers use a few different standardized communications protocols. This was to allow a generic scan tool to be used on all OBDII equipped systems.

Due to improved technology and resolving compatibility issues in communication, manufacturers are now phasing in a common communication protocol: Controller Area Network (CAN).

By the model year 2008 all manufacturers must communicate to OBD II approved scan tools using CAN. Phase in began in 2003.

Controller Area Network (CAN)

• • • The CAN communication system operates over two wires in the DLC at much faster rates than any previous communication protocol.

Vehicles communicating with CAN are capable of providing over 200 data parameters with a greatly increased update rate.

Many OBD II scan tools will not be able to communicate with CAN vehicles unless they are upgraded or replaced. Most scan tool manufacturers have already produced updates or new tools, contact your provider for more information.

DLC DLC

CAN will use pins 6 and 14

All connectors should also have pins 4 (Chassis Ground), 5 (Signal Ground), and 16 (Battery Positive).

Pin 2 Pin 6 Pin 7 Pin 10 Pin 14 Pin 15 Standard

USES USES USES USES J1850 PWM J1850 VPW USES USES ISO9141/14230 KEYWORD ISO15765 CAN 9

DLC Location

• The diagnostic connector is required to be located between the driver’s end of the instrument panel and approximately one-foot beyond the vehicle centerline, on or below the instrument panel. • On most vehicles, the connector is located beneath the instrument panel, near the steering column. And the connector is usually exposed.

• Some vehicles have hard to find DLCs.

Typical DLC Location

Not So Typical DLC Locations Back Seat

Hidden Behind Cover

Hidden Behind Two Covers

Hidden Behind Wood Cover

% of Vehicles with Communication Problems

2.50% 2.00% 1.50% 1.00% 0.50% 0.00% No COM No DLC OR WI IL

READINESS

• OBDII systems have up to 11 diagnostic monitors. Diagnostic monitors are periodic tests run on specific systems and components to ensure that they are performing within their prescribed range.

• OBDII systems must indicate whether or not the onboard diagnostic system has monitored each component or system. • Components or systems that have been diagnosed are termed “ready”. This means they were tested,

not

that they passed the test.

• The purpose of recording readiness status is to allow technicians to determine if the vehicle’s OBDII system has tested the components and/or systems.

READINESS (Continued)

• Once a monitor has been set to “ready”, it will continue to indicate “ready” unless the vehicle’s battery is disconnected or codes are cleared, with a few exceptions.

• Normally, the readiness status of all components or systems will be “ready”. • However, if the vehicle’s PCM (Powertrain Control Module (PCM is OBD II terminology for the powertrain computer) has lost power, or if DTCs have been recently cleared with a scan tool, all non-continuous components or systems will be set to “not ready”.

% of Vehicles Not Ready

(>2 Monitors Not Ready)

12.00% 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 1996 1997 1998 Overall OR WI IL CA TX

Non-Continuous Monitors

• The monitors listed below are termed non-continuous monitors:   02 Sensor O2 Sensor Heater   Catalyst Evaporative System  EGR System   Secondary AIR System Others if vehicle is so equipped (heated catalyst, and A/C system) • Readiness is an issue only with these non-continuous monitors.

Enabling Criteria

• Non-continuous monitors can only run (test the system) when the vehicle conditions are appropriate for testing. These operating parameters are typically termed enabling criteria.

• As an example, the catalytic converter could not be tested when the vehicle was cold (the cat was not “lit”) or when the throttle was wide open (no converter can manage full enrichment emissions). The PCM could also not test the system if a major input signal was faulty, if the Mass Airflow (MAF) sensor or an O2S were faulty, the PCM would not be able to regulate fuel or evaluate the converter.

Typical Criteria for EVAP Monitor

• No DTCs set • Barometric pressure exceeds 75 KPA (below roughly 14,000 feet • At start-up, IAT & ECT is between 40º and 100º F • ECT is not more than 12º greater than IAT • Fuel tank level is between 25% and 75% • The TPS is between 9% and 35% • The EVAP purge solenoid is at 50% PWM within 65 seconds of run time Whenever these criteria are met the PCM will run the EVAP monitor 23

Oxygen Sensor Monitor

• The Oxygen Sensor (O2S) Monitor consists of two tests: • Sensor amplitude test -- The PCM switches the air fuel ratio rich and lean to see that the O2S can produce a voltage at the low and high threshold, typically .2 and .8 volts.

• Sensor switch rate test – The PCM switches the air fuel ratio at a specified rate and watches the rate of change from the O2S above and below the rich lean threshold. It must typically switch in 50 to 100 milliseconds.

Oxygen Sensor Heater Monitor

• The Oxygen Sensor (O2S) Heater Monitor tests to be sure that the heater circuit is functional.

• Manufacturers perform this testing using several different methods. Typical tests include: testing after a cold start and watching the time until O2S activity; monitoring current flow through the heater element; and cycling the heater on and off and watching the change in current as resistance increases.

% of Vehicles with O2S Monitor Not Ready

12.00% 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 1996 1997 1998 Overall OR WI IL CA TX

% of Vehicles with O2S Heater Monitor Not Ready

8.00% 7.00% 6.00% 5.00% 4.00% 3.00% 2.00% 1.00% 0.00% 1996 1997 1998 Overall OR WI IL TX

Catalyst Monitor

• The three-way catalytic converter is used to convert the primary exhaust pollutants (HC, CO and NOx) into carbon dioxide (CO2), water (H2O) and nitrogen.

• The cat monitor diagnoses the catalytic converter by comparing the signal between the upstream and downstream oxygen sensors.

• The catalyst must be 60% efficient to pass the test. Many early OBD II vehicles are now failing this test and setting a P0420 DTC.

Catalyst Monitor Passed

The pre-cat O2S in red is switching normally. At the mid point of the recording the PCM begins the catalyst monitor by switching the A/F ratio at a steady and high frequency. The front O2S shows fine amplitude and switch rate.

The post-cat O2S in blue is staying steady both before and after the test. This indicates that the converter is doing its job of using oxygen to oxidize hydrocarbons.

Catalyst Monitor Failed

Again, during the mid point of the recording, the PCM “feeds” the cat and watches the rear O2S response, in blue. The post-cat O2S response rate is almost identical to the front O2S. It is unable to oxidize the hydrocarbons.

This recording is of a 1996 vehicle with 122,000 miles with a DTC P0420, Low Catalyst Efficiency. The previous slide showed the same vehicle with a new converter installed.

% of Vehicles with CAT Monitor Not Ready

25.00% 20.00% 15.00% 10.00% 5.00% 0.00% 1996 1997 1998 Overall OR WI IL CA TX

EVAP Monitor

• Non-enhanced systems used between 1996 and 1999 tested the system only to verify purge flow.

• Enhanced systems were phased in beginning in 1996 at 20%, 1997 at 40%, 1998 at 90% and 2000 at 100%. Enhanced systems were required to check for EVAP system leaks.

• Early enhanced EVAP systems were designed to detect a level of HC loss equal to or greater than an opening in the system of 0.040”. 2000 and newer EVAP systems check for a .020” leak.

% of Vehicles with EVAP Monitor Not Ready

16.00% 14.00% 12.00% 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 1996 1997 1998 Overall OR WI IL CA TX

EGR Monitor

• The EGR system recirculates non-combustible exhaust gases back into the cylinder to dilute the incoming air/fuel charge.

This cools the combustion chamber down and reduces Oxides of Nitrogen (NOx).

• The EGR system is monitored for high and low flow rates, sensor and output failures, and lack of correlation indicated flow.

between PCM commands and • The system monitor may use a MAP, DPFE, or an exhaust gas temperature sensor, or Long Term Fuel Trim (LTFT) to evaluate EGR flow.

% of Vehicles with EGR Monitor Not Ready

10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 1996 1997 1998 Overall OR WI IL TX

• •

Other Non-Continuous Monitors

Secondary Air Injection Monitor --

If the vehicle is equipped with an air injection system, it must be monitored for flow. Modern AIR systems use an electric pump for 90 seconds after start-up to pump air to the exhaust manifold to reduce cold-start emissions by oxidizing HC and CO in the manifold and heating up the converter faster. The monitor typically watches the O2S while the pump is energized.

Heated Catalyst and A/C System --

R12 as an A/C refrigerant.

If the vehicle is equipped with a heated catalyst, then it must be monitored. Also, if the vehicle uses R12 as an A/C refrigerant, then the A/C system must be monitored for leaks. Currently, no vehicles sold in the U.S. use 36

Continuous Monitors

Some of the vehicle continuously tested by the components or systems are vehicle’s OBDII system, while others are tested only under specific vehicle operating conditions.

The continuously monitored components listed below are always ready:  Fuel System  Misfire  Comprehensive Components 37

Misfire Monitor

• • Monitoring misfires and identifying offending cylinders is a requirement of OBDII. This is typically accomplished by monitoring crankshaft deceleration. If a cylinder does misfire fully or partially, the reduced force on the piston slows down the crankshaft.

The monitor looks for a change in crankshaft speed as indicated by a change in the pulse width or frequency outputted by the crankshaft position sensor.

• • •

Fuel System Monitor

Using feedback from the oxygen and other sensors, the PCM manages the fuel system to optimize engine combustion conditions.

OBDII regulations require that the fuel system be continuously monitored. The MIL is illuminated if the fuel system cannot be controlled by the PCM.

Criteria for setting the MIL varies by manufacturer but typically if LTFT is above + 20 25% or if it is below -20-25% a lean (+20) P0171 DTC, or rich (-20) P0172 DTC is set.

Comprehensive Components Monitor

• The on-board system must check for malfunctions in any electronic component or system that either provides input to, or receives commands from the PCM for emissions control.

• Sensor inputs are to be tested for functionality (is it working?) and rationality (do the readings make sense?).

Functional Checks

• • Functional tests are performed between key on and key crank. The PCM sends a small current through components and monitors return.

Example: Circuit Continuity – Problems with circuit continuity include any type of electrical circuit fault, (open circuit, short to voltage or ground) switch or sensor failures, (opens, internal shorts, shorts to ground or voltage) and PCM internal problems.

Rationality Checks

• • The PCM tests sensors to be sure their signals make sense by comparing them with other inputs.

Example -- the Throttle Position Sensor --If the engine speed is high, engine load indication is high and airflow is high, but the Throttle Position signal indicates a closed throttle condition, then the OBDII system must detect the fault and set an appropriate DTC.

How Monitors Become Ready

• The PCM sets a monitor to “ready” after an appropriate drive cycle has been performed within one key-on, engine-run, key-off cycle. • The drive cycle that enables a monitor and sets readiness codes to “ready” varies for each individual monitor. This monitor specific drive cycle is frequently called a “trip”.

• Normal driving usually sets a monitor to ready in a couple days.

THIS GENERIC DRIVE CYCLE IS INTENDED TO ALLOW ALL THE MONITORS TO RUN.

Getting Vehicles Ready (cont.)

• • If the driving habits of the vehicle owner or environmental conditions are such that an appropriate drive cycle has not been completed, the monitors will not be ready. As an example, the catalytic converter will generally only be monitored when the vehicle is fully warm, at highway speed, and under light load. A vehicle that never sees these conditions, this trip, will never be ready, since the cat monitor will never run.

SOME VEHICLES ARE HARD TO GET READY

• The following vehicles are exempted from readiness requirements in Delaware: – 1996 Subaru (all models) – Monitors sets to not ready when engine is turned-off.

– 1996 - 1998 Mitsubishi (all models) – Requires all monitors to run in 1 or 2 trips. – 1996-1998 Volvos – 1996 Mercedes – 1996 Hyundai 47

INFORMATION ON HOW TO GET VEHICLES READY

• • • • • • iATN: www.iatn.com

, technical resources Manufacturer’s websites: List available at www.nastf.org

, OEM service matrix OBDII clearinghouse: www.obdclearinghouse.com

. CSU OBD website: www.ncvecs.colostate.edu

Many scan tools have monitor criteria available In the future, EPA will mandate that drive cycles for all 1996 and newer vehicles must be publicly available.

MALFUNCTION INDICATOR LAMP (MIL)

• The Malfunction Indicator Lamp (MIL) is the official term for the warning light that is illuminated by the vehicle’s OBD system when a malfunction occurs. • Before OBDII, the criteria to illuminate the warning light was not consistent among the vehicle manufacturers.

Malfunction Indicator Lamp (MIL)

MIL Illumination Criteria

• The purpose of the MIL is to alert the driver to the malfunction so repairs can be performed in a timely manner.

• The MIL illuminates when a failure occurs which could cause vehicle emissions to exceed 1.5 times their designed standard. This may include sensors that do not immediately impact emissions and often include transmission codes, such as TCC or a shift solenoid, that clearly will effect emissions.

• The MIL also illuminates when a problem is detected in a component that is used as part of the diagnostic strategy for any other monitored system or component. • The MIL can only be used to indicate actual problems in the emission control system. It cannot be used as a maintenance reminder, e.g., change oil.

Types of MIL Illumination

 When severe misfire occurs that could damage the catalytic converter, the MIL is required to flash on and off once per second.

Flashing is intended to discourage vehicle operation.

 Constant illumination of the MIL (i.e., it is not flashing) indicates that a problem has been detected and the vehicle should be serviced as soon as possible.

Can

PCM

Turn MIL Off?

• • The powertrain control module (PCM) can turn the MIL off if the problem does not reoccur for three consecutive trips. For some monitors, the vehicle must be operated under similar conditions to those that occurred when the vehicle originally illuminated the MIL before the MIL can be turned off.

MIL Status

• MIL status refers to whether or not the PCM has commanded the MIL to be on.

•

The purpose of checking MIL status using the inspection system is to determine if the vehicle’s OBD system has commanded the MIL to turn on based on a malfunction. This allows you to determine if there is a malfunction, even if the MIL is not actually illuminated, The MIL may not be on because of a problem with the MIL itself, or due to tampering with the MIL.

% of Vehicles with MILs Commanded On

16.00% 14.00% 12.00% 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% 1996 1997 1998 Overall OR WI IL

12%

Oregon’s OBD MIL Rate by Vehicle Mileage?

11.18% 10% 8% 7.33% 6% 4% 2% 0% 3.86% 1.44% 26-50 >100 76-100 51-75 Miles (x1,000) 0.82% 0-25

Oregon’s OBD MIL Rate vs Mileage for Model Year 1996?

17% 16% 15% 14% 13% 12% 11% 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 0% 15

y = -8E-06x 3 + 0.0005x

2 - 0.0025x + 0.0365

R 2 = 0.9472

25 35 45 55 65 75 85

Mileage (x1,000) Bins

95 105 115 125 59

Oregon’s OBD MIL Rate vs Mileage for Model Year 1997?

17% 16% 15% 14% 13% 12% 11% 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 0% 15

y = 3E-06x 3 + 0.0001x

2 - 0.0001x + 0.0107

R 2 = 0.9825

25 35 45 55 65 75 85

Mileage (x1,000) Bins

95 105 115 125 60

Visual Inspection of Malfunction Indicator Lamp (MIL)

• In many OBDII I/M programs, inspectors perform visual checks of the MIL: – Key-On Engine Off (KOEO) – Key-On Engine Running (KOER) • In DE inspectors only perform a KOER visual check if the vehicle will not communicate.

Visual Inspection of Malfunction Indicator Lamp (MIL) -- key on, engine off – (KOEO)

• The inspector determines if the instrument panel Malfunction Indicator Lamp (MIL) illuminates when the ignition key is turned to the “key on, engine off” (KOEO) position. •

On most vehicles, the MIL will stay illuminated as long as the key is in the “key on, engine off” position. However, on some vehicles, e.g., Chryslers Hondas/Acuras, the MIL will illuminate very briefly when the key is turned to the “key on, engine off” position and then will go out. This is acceptable.

Visual Inspection of Malfunction Indicator Lamp (MIL) -- key on, engine running – (KOER)

• Some programs perform the KOER check.

• The inspector starts the engine and then determines if the MIL is illuminated while the engine is running.

Sometimes inspectors look at the wrong light!

• • • The MIL will say “Service Engine Soon,” “Check Engine,” or use the international engine symbol.

Maintenance reminder lights are not MILs.

Vehicles should not be failed if their maintenance reminder lights are on, but sometimes they are.

DRIVER UNDERSTANDING OF MIL

• • • Focus group studies find that motorists do not understand the MIL.

Confused and concerned by light – Immediate breakdown? – Need to pull over?

– Over-heating?

– Time for routine maintenance?

Virtually no understanding of link with emissions 69

Understanding of MIL

• • • General nature of message “Check Engine” or “Service Engine Soon” and mysterious icon (radiator? submarine? helicopter? coffeepot?) add to confusion Some: “Flashing light indicates more serious problem” Others: “Flashing light indicates less serious problem (bad light or system can’t make up it’s mind)” 70

“My first thought was ‘What’s my engine temperature?’ I’m always worried that it’s going to blow up.” “I would stop. I’m very car-illiterate... I would stop and look in the manual.” “I would have pulled over and looked for something obvious — something over-heating or leaking or a broken belt.” “Every 2000 miles the “Check Engine Light comes on when your engine needs to be serviced, and they just re set it.” 71

“When it came on before, I ended up taping over it because it wouldn’t go off. I asked my mechanic about it, and he said I didn’t have to worry bout it. It’s just routine. They come on at a certain mileage interval when maintenance is due. You can have it re set, or you can use duct tape.” “I heard from my in-laws that it was a routine issue that would not affect the car’s functioning... and it would be okay to ignore it. It kept going on and off. I ignored it for a year until I traded in the car.” “I checked the manual. The way the manual was written was like ’Stop immediately. Get off the road. Call your dealer’ ... It said something serious was wrong. I brought it in, they looked it over, and said it was just a malfunction of the light. There was nothing wrong with it.” 72

DIAGNOSTIC TROUBLE CODES (DTCs)

• Whenever the MIL is illuminated a DTC should be stored in the PCM.

• Before OBDII, each manufacturer had their own specific trouble code list and code definitions. • Under the OBDII requirements, all manufacturers must comply with a standardized convention for DTCs. • The universal DTC format consists of a 5 character alphanumeric code, consisting of a single letter character followed by four numbers.

NEW DTC STRUCTURE

DTC LISTINGS

A listing of DTCs, including P0, P1, P2A, P2 and P3 generic codes are available at IATN, www.iatn.com

under the technical resources list. The list can be printed or downloaded for easy access in your shop.

What Sets a DTC?

• DTCs are set when a monitor identifies a problem.

• Many diagnostic monitors do not turn the MIL on when the vehicle fails a test for the first time. Instead a “pending code” is set.

• If the test fails on a second consecutive trip, however, the MIL is illuminated and a DTC is stored.

Freeze Frame

• When an emission related malfunction occurs that illuminates the MIL, vehicle-operating parameters are to be stored in the PCM.

• The freeze frame data is stored for the first DTC that is set. It can only be overwritten by a Misfire or Fuel Trim DTC.

Freeze Frame Parameters

• engine rpm • vehicle speed • air flow • engine load • fuel pressure • fuel trim value (i.e., rich or lean) • engine-coolant temperature • intake manifold pressure • open or closed loop status 78

DTCs in Vehicles Failing OBDII Tests

• OBDII Tests provide a reliable means of recording specific problems that occur in the vehicle fleet.

• This analysis focuses on DTCs recorded in Delaware, New Jersey, Illinois, Wisconsin, and Oregon 79

Relationship Between Tailpipe Test Results and OBD Results • Arizona did a test program where 5,000 vehicles received OBD tests and IM147 Transient Tests.

• Wisconsin performs IM240 tests on vehicles that are not ready or do not communicate with scan tool.

# of DTCs in Vehicles with MILs Commanded On

60.00% 50.00% 40.00% 30.00% 20.00% 10.00% 0.00% 1 2 3+ CA CT DE

Maximum Number of DTCs Observed

• California: >10 • Connecticut: 24 • Delaware: 15 82

What Are California’s Top Ten Diagnostic Trouble Codes?

Rank DTC 1 P0420 -- Low Catalyst Efficiency 2 P0171 -- System Too Lean 3 P0401 -- EGR Flow Insufficient 4 P0174 -- System Too Rich 5 P0300 -- Random Misfire 6 P0141 -- 02 Sensor Heater Circuit Malfunction 7 P1443 -- Ford Evap Control Valve Failure 8 P0135 -- 02 Sensor Heater Circuit Malfunction 9 P0133 -- 02 Sensor Circuit Slow Response 10 P0455 -- Evaporative Emission Control System Leak Detected (gross leak)

Total Top 10

3.4%

58.5%

% 10.7% 10.1% 7.0% 6.0% 4.6% 4.5% 4.2% 4.0% 3.9% 83

What Are Connecticut’s Top Ten Diagnostic Trouble Codes?

Rank DTC 1 P0420 -- Low Catalyst Efficiency 2 P0171 -- System Too Lean 3 P0401 -- EGR Flow Insufficient 4 P0174 -- System Too Rich 5 P0300 -- Random Misfire 6 P0141 -- 02 Sensor Heater Circuit Malfunction 7 P0133 -- 02 Sensor Circuit Slow Response 8 P0325 -- Knock Sensor 1 Circuit Malfunction 9 P0135 -- 02 Sensor Heater Circuit Malfunction 10 P0440 -- Evaporative Emission Control System Malfunction

Total Top 10

% 11.1% 9.9% 7.9% 5.6% 5.1% 4.9% 4.4% 4.2% 4.1% 3.8%

61.0%

What Are Delaware’s Top Ten Diagnostic Trouble Codes?

Rank DTC 1 P0420 -- Low Catalyst Efficiency 2 P0171 -- System Too Lean 3 P0401 -- EGR Flow Insufficient 4 P0300 -- Random Misfire 5 P0174 -- System Too Rich 6 P0141 -- 02 Sensor Heater Circuit Malfunction 7 P0133 -- 02 Sensor Circuit Slow Response 8 P0301 -- Misfire Cylinder 1 9 P0304 -- Misfire Cylinder 4 10 P0135 -- 02 Sensor Heater Circuit Malfunction

Total Top 10

% 9.8% 9.4% 8.9% 7.7% 5.2% 4.8% 4.7% 4.7% 4.0% 3.7%

62.9%

Top 10 Comparison

DTC

P0420 -- Low Catalyst Efficiency P0171 -- System Too Lean P0401 -- EGR Flow Insufficient P0174 -- System Too Rich P0300 -- Random Misfire P0141 -- 02 Sensor Heater Circuit Malfunction P1443 -- Ford Evaporative Control Valve Failure P0135 -- 02 Sensor Heater Circuit Malfunction P0133 -- 02 Sensor Circuit Slow Response P0455 -- Evaporative Emission Control System Leak Detected (gross leak)

10 1 2 3 4 8 9 5 6 7

5 6 14 1 2 3 4 9 7 13

4 6 21 10 7 1 2 3 5 15 86

DTC

What Are the Most Common P1XXX Codes?

CA Rank CT DE

P1443 -- Ford Evaporative Control Valve Failure P1131 -- Ford Heated O2 Sensor P1870 -- GM Internal Transmission Component Slipping 7 17 18 14 28 30 21 22 23 87

CA DTCs – Pass or Fail ASM Test

• • • CA performs tailpipe and OBDII tests on 1996+ vehicles.

DTCs were tabulated for vehicles that failed the ASM test, and for vehicles that passed the ASM test.

Some significant differences and similarities are apparent.

CA DTCs – Failed ASM Test

Most Frequent DTCs in Vehicles That Fail ASM Test

25.0% 20.0% 15.0% 10.0% 5.0% 0.0% P0420 P0135 P0401 P0133 P0171 P0134 P0300 P0141 P0301 P0400 89

CA DTCs – Passed ASM Test

Most Frequent DTCs in Vehicles That Pass ASM Test

14.0% 12.0% 10.0% 8.0% 6.0% 4.0% 2.0% 0.0% P0171 P0420 P0401 P0174 P1443 P0141 P0300 P0455 P0133 P0440 90

CA DTCs – Failed ASM Test

Rank DTC

1 P0420 -- Low Catalyst Efficiency 2 P0135 -- 02 Sensor Heater Circuit Malfunction 3 P0134 -- 02 Sensor Circuit No Activity Detected 4 P0113 -- Intake Air Temperature Circuit High Input 5 P0401 -- EGR Flow Insufficient 6 P0133 -- 02 Sensor Circuit Slow Response 7 P0171 -- System Too Lean 8 P0300 -- Random Misfire 9 P0400 -- Exhaust Gas Recirculation Flow Malfunction 10 P0141 -- 02 Sensor Heater Circuit Malfunction

% of DTCs in ASM Fails

31.66% 35.03% 54.99% 30.10% 14.19% 27.70% 9.29% 20.89% 29.93% 16.29% 91

CA DTCs – Passed ASM Test

Rank DTC

1 P0171 -- System Too Lean 2 P0420 -- Low Catalyst Efficiency 3 P0401 -- EGR Flow Insufficient 4 P1443 -- Ford Evaporative Control Valve Failure 5 P0455 -- Evaporative Emission Control System Leak Detected 6 P0141 -- 02 Sensor Heater Circuit Malfunction 7 P0113 -- Intake Air Temperature Circuit High Input 8 P0300 -- Random Misfire 9 P0133 -- 02 Sensor Circuit Slow Response 10 P0440 -- Evaporative Emission Control System Malfunction

% of DTCs in ASM Passes

90.71% 68.34% 85.81% 89.27% 96.03% 83.71% 69.90% 79.11% 72.30% 93.39% 92

Conclusions About DTCs

• • • • Top 10 DTCs are nearly identical in Federal and California vehicles.

The top 10 DTCs are present in about 60% of the MIL On cases. States can jointly develop training programs to diagnose the top 10 DTCs About 45% of the OBD Fails have more than 1 DTC. These cases must be addressed by training.

The most frequent DTC in ASM failures was P0420 (low catalyst efficiency). But a majority of the P0420 codes were in vehicles that pass the ASM. Tailpipe tests are not sensitive enough to identify many cases of low catalyst efficiency,

but they’re better than nothing

Relationship Between Tailpipe Test Results and OBD Results • Arizona did a test program where 5,000 vehicles received OBD tests and IM147 Transient Tests.

• Wisconsin performs IM240 tests on vehicles that are not ready or do not communicate with scan tool.

INITIAL IM147 EMISSION LEVELS Arizona

1.2

1 0.8

g/mi 0.6

0.4

0.2

0 HCx2 CO/10 NOx Fail OBD Pass OBD

WISCONSIN RESULTS: IM240 Emissions (g/mi.) vs. Ready Status

0.6

0.5

0.4

0.3

0.2

0.1

0 HC CO/10 NOx Not Ready No COM

OBD TESTS ON HIGH MILEAGE TAXIS

As part of a pilot OBD-II test program in Austin Texas, high mileage taxis were inspected. Inspections confirmed that OBDII systems work well on extremely high mileage vehicles.

TEXAS RESULTS -- Yellow Cab

Number of tests: 197 Fail for MIL on: 34.2% Fail for unset readiness codes: n Any: 29.6% n More than 2: 9.2% Fail for MIL on or more than 2 monitors not ready: 38.8% 98

TEXAS RESULTS Yellow Cab: % MIL On by Odometer

70.00% 60.00% 50.00% 40.00% 30.00% 20.00% 10.00% 0.00% <100K 100K 200K >200K

TEXAS RESULTS Yellow Cab: % Not Ready by Odometer

50.00% 40.00% 30.00% 20.00% 10.00% 0.00% Any >2 <100K 100-200K >200K

100

TEXAS RESULTS -- Yellow Cab

• Common trouble codes:  Catalytic Converter: 60.0% of MIL-On cases – Catalyst alone: 38.5%, Catalyst + Others: 21.5%  MIL-On Cases without Catalyst Codes (Misfire, EGR, Air Fuel, and Oxygen Sensors were most common codes): 40% 101

Future OBD and Diagnostic Requirements

• Additions to OBDII Requirements • Service Information Requirements • OBDIII 102

NEW OBD REQUIREMENTS

• • • • PCM VINs on all vehicles – Great anti-clean scanning tool Clear Code History: Key-starts since codes were cleared – Can tell if codes were cleared just prior to inspection Mandatory Monitoring Intervals – May allow DMV to tighten readiness requirements Permanent DTCs – DTCs are only cleared by the computer after the fix has been confirmed.

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NEW OBD REQUIREMENTS

•

Drive cycle info:

– Require drive cycles, drive cycle info, or monitoring conditions to be made available (for all 1996 and newer) to exercise monitors needed to set readiness codes. – New Vehicles -- Must allow technicians to be able to operate all the diagnostics on a single drive cycle. –

Helps technicians and motorists get cars “ready” for the inspection and verify repair effectiveness.

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EPA’s Recent and Proposed Revisions to Service Information

• Recent and proposed revisions – Web based access to information - passed – Access to OEM training - passed – New definition of “emissions-related” information - passed – New technology for reprogramming - revisions – Scan tool information - revisions – Heavy-duty Service Information - revisions 105

OEM Web Site Requirements

• Require OEMs to launch individual Web sites that have required information in full text – Home page • • • Accessible to anyone Instructions on accessing information Cost and payment options – No use of proprietary hardware, software, viewers, browsers, and formats 106

Proposed Web Site Requirements

• MYs included – likely to propose 96 and later to coincide with full implementation of OBDII • Upload information within 3 months of model introduction and maintain for 15 years • Archive info after 15 year window expires 107

EPA Proposed Training

• Propose manufacturers do the following: – Manuals, videos, CD-ROMs, video tapes of Internet and satellite transmissions made available by OEMs for purchase on their Web sites.

– Provided to third party that delivers it to aftermarket.

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Proposed Scan Tool Requirements

• Make all OEM-specific diagnostic tools available for sale • Make all generic and enhanced emissions related information available to tool companies 109

RECOMMENDED DIAGNOSTIC/REPAIR PROCEDURE FOR OBDII FAULTS

• • • • • • • Verify customer complaint Check and record DTCs and Freeze Frame Data Perform thorough visual inspection Check Technical Service Bulletins Understand and Test System or Component Repair as Needed Verify Repair and run monitor if feasible 110

VCERTT CASE STUDY #1

P0420 CATALYST EFFICIENCY • • • Customer came with concern of bucking and hesitation and the MIL on. The vehicle was a 95 OBD II Subaru.

We attempted to verify customer concern. We could not duplicate complaint during normal nor aggressive driving. Checked MIL status, DTCs and Freeze Frame Data.

– MIL commanded ON – DTC P0420 Low Catalyst Efficiency – Freeze frame showed engine warm, light load, cruising speed, typical of catalytic converter monitor conditions.

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VCERTT CASE STUDY #1

P0420 CATALYST EFFICIENCY • • • • We did perform a visual inspection of the converter which showed no damage or signs of restriction. We also checked the ignition system for obvious signs of misfire but found none.

Next we checked for TSBs but found none appropriate to the concern.

We decided to concentrate on misfire, knowing that extended misfire is likely to cause converter damage.

We drove the vehicle again. We lugged the vehicle significantly and pushed it uphill at full throttle. We finally achieved misfire and the MIL flashed.

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P0420 CATALYST EFFICIENCY and CUSTOMER CONCERN OF MISFIRE • • • We rechecked for DTCs and now found P0303, cylinder #3 misfire along with the P0420 We inspected the platinum plug; it looked great. We swapped it with cylinder #1, cleared the codes and road tested. Returned with the same P0303. Repeated process with wire swap with same result.

Next we sprayed coil pack and loaded engine to check for voltage leak or tracking, none observed. We also visually inspected coil.

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DIAGNOSING P0303 AND CUSTOMER CONCERN OF MISFIRE Cylinder #3 tower corroded 114

P0303 DIAGNOSIS, REPAIR AND VERIFICATION • • • We did test resistance and output of the suspect coil. It passed the tests but knowing this was a pattern failure on this vehicle and having suitable reasons for a conclusion, we replaced the coil pack.

We cleared the codes, sprayed the coil and wires down and drove the vehicle as hard as ever. The MIL stayed off and we felt absolutely no misfire. We repeated the road test several times.

We felt confident that we had repaired the customer concern of bucking and hesitation.

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P0420 REPAIR AND VERIFICATION • • • Next we drove the vehicle twice under the conditions required for the catalyst monitor to run. We were able to set the monitor to ready and sure enough P0420 reappeared.

We explained our findings and reasoning to the vehicle owner and recommended that we replace the faulty converter.

After replacing the converter we verified our repair by again running the catalyst monitor. At ready we had no pending code, at second trip we had no DTC. The waveforms of O2Ss shown earlier in presentation were of this case study.

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CASE STUDY #1 CONCLUSIONS • We did concentrate on customer concern, knowing it could be the cause of DTC. Typically you would repair system or component related to DTC first.

• We repaired customer concern and verified repair. • We communicated effectively with owner, knowing that repairs would be costly and symptoms did not, to the lay person, correlate with the DTC.

• We made repair related to DTC and verified that repair.

• We checked back with customer a few weeks later to confirm repair and verify satisfaction.

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CASE STUDY #1 CONCLUSIONS (CONT.) • The combination of repairs led us to believe that we had determined the root cause of the P0420 DTC.

• Clearing DTCs would not have been an effective strategy and would have led to a comeback.

• Although this was a converter DTC, it is important to explain to customers with misfire DTCS that it is possible that damage to the converter occurred. A 420 DTC may not have set yet because converter monitoring was suspended. They may be faced with another DTC for low catalyst efficiency that would require converter replacement. This discussion covers your work and reputation.

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• • • • • •

VCERTT CASE STUDY #2

P0130 and P0133 OXYGEN SENSOR The vehicle was a 1996 Toyota Tacoma with about 114,00 miles on it.

We verified the customer concern of reduced fuel economy and MIL on.

Verified Mil Status and DTCs P0130-O2S Circuit B1S1 and P0133-O2S Circuit Slow Response B1S1.

We recorded DTCs and Freeze Frame Data.

We test drove the vehicle to feel for any other drivability issues; the truck ran well.

We performed a visual check of the B1S1 O2S. These are bolted on with a plate and notorious for rust and connector corrosion. This sensor looked fine.

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OXYGEN SENSOR DTC AND LOW MPG

• We searched for but found no relevant TSBs.

• Our first test of the O2S was to be sure that the heater circuit was working. It had 12 volts and ground to it with the key on.

• We ran the vehicle and monitored the O2S voltage with our digital multimeter (DMM). We looked to see that the sensor switched regularly below .4 and above .6 volts, hoping to see .2 and .8 frequently. It “seemed ok” but we knew that test was inconclusive.

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OXYGEN SENSOR DTC AND LOW MPG

• We took several recordings of the O2S at idle and at 2,500 rpm and viewed the MIN/MAX/AVG results. We did see high and low voltages, but the average was .2 or .3 volts consistently. We pulled a spark plug and it was black/rich.

• We also ran the vehicle on the dyno and watched the emissions and calculated fuel economy for later comparison. The vehicle HC and CO was high, the NOx was low. Fuel economy was below 24 mpg.

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O2S DIAGNOSIS AND REPAIR

• With a lean-biased O2S and rich spark plugs we were quite confident that we were in fact dealing with a faulty O2S.

• In the luxury of our case study time, we also took a scope recording which did show slow transition.

• We replaced the O2S and retested the sensor with a MIN/MAX/AVG and scope recording. Both showed a healthy O2S.

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O2S REPAIR VERIFICATION

• • • To verify our repair we ran the vehicle on the dyno again to try to run the O2S monitor and to calculate MPG.

We succeeded in setting the O2S monitor to ready and found no pending DTCs. The MPG improved by 30% with the new O2S installed.

We followed up with the customer after on month and found her happy with improved mileage and no MIL.

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CASE STUDY #2 CONCLUSIONS

• We verified the customer concern of the MIL on and considered causes of low MPG.

• We tested appropriately and felt confident (even without our “case study time luxury”) that we found the root cause of both concerns. • We verified the repair through retesting the sensor and running the O2S monitor.

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CASE STUDY #2 CONCLUSIONS

• • We did discuss the possibility of converter damage and a subsequent P0420 given the rich condition.

We communicated with the customer at the time of repair and one month after.

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VCERTT General Diagnosis / Repair Conclusions • Verify customer concern.

• This is critical to customer satisfaction.

Don’t just clear codes to turn off MIL – Doesn’t correct problem, and usually results in unhappy customer • Thorough visual check is necessary – ~30% of problems can be identified visually 126

VCERTT General Diagnosis / Repair Conclusions • • • Check Technical Service Bulletins – Many common failures have TSBs that save time, money and may be the only way to resolve concern.

Need to confirm repair – Without confirmation you are wide open for comeback Check back with customer after repair This can save you many customers 127

SHOULD A TECHNICIAN CLEAR CODES IF THE SYSTEM IS

• • •

CONTINUOUSLY MONITORED?

Some vehicles appear to be retested without having codes cleared, since the MIL was off but the code was present.

This practice avoids problems with vehicles being not ready for retests.

Be sure you have verified the repair.

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