P02AB Fuel cylinder 5 piping at minimum limit

P02AB Fuel cylinder 5 piping at minimum limit

OBD-II DTC Datasheet

Adjusting the fuel level of cylinder 5 at the minimum limit

What does this mean?

This is a generic powertrain diagnostic trouble code (DTC) and is commonly applied to all gasoline OBD-II vehicles. This may include but is not limited to Mazda, Land Rover, Jaguar, Subaru, Ford, BMW, Dodge, etc. Despite the general nature, the exact repair steps may vary depending on the year of manufacture, make, model and configuration. transmissions.

A stored P02AB code means the powertrain control module (PCM) has detected an extremely rich mixture condition in a specific cylinder in the engine, in this case cylinder # 5.

The PCM uses a fuel trim system to increase or decrease fuel delivery as needed. The oxygen sensor inputs provide the PCM with the data it needs to adjust the fuel trim. The PCM uses fuel injector pulse width modulation variations to change the air / fuel ratio.

The PCM continuously calculates short term fuel trim. It fluctuates quickly and is one of the key factors in calculating the long term fuel consumption correction. Each vehicle has minimum and maximum fuel trim percentages programmed into the PCM. The parameters for short term fuel trim are much broader than the parameter specifications for long term fuel trim.

Small deviations in fuel trim, usually measured in positive or negative percentages, are normal and will not result in a P02AB code being stored. The maximum fuel trim parameters (positive or negative) are usually in the twenty-five percent range. Once this maximum threshold is exceeded, this type of code will be saved.

When the engine is operating at optimum efficiency and there is no need to increase or decrease the amount of fuel supplied to each cylinder, the fuel consumption adjustment should reflect between zero and ten percent. When the PCM detects a lean exhaust condition, the fuel needs to be increased and the fuel consumption correction will reflect a positive percentage. If the exhaust is too rich, the engine needs less fuel and the fuel consumption adjustment should reflect a negative percentage.

See Also: Everything You Want To Know About Fuel Trims.

OBD-II vehicles will need to establish a pattern for a long term fuel trim strategy, which will require multiple ignition cycles.

Fuel Trim Graphs Shown by OBD-II:

What is the severity of this DTC?

P02AB should be classified as heavy as rich fuel can lead to numerous drivability problems and damage to the catalytic converter.

What are some of the symptoms of the code?

Symptoms of a P02AB trouble code may include:

• Reduced engine performance
• Reduced fuel efficiency
• Delayed engine start
• Presence of Saved Saturated Exhaust Codes
• Misfire codes can also be saved

What are some of the common causes for the code?

Reasons for this P02AB fuel trim code may include:

• Defective fuel injector
• Bad fuel pressure regulator
• Defective oxygen sensor
• Malfunction of the mass air flow (MAF) or manifold air pressure (MAP) sensor

What are some steps to troubleshoot P02AB?

If there are codes related to MAF or MAP, diagnose and repair them before attempting to diagnose this P02AB code.

I would start my diagnosis with a general inspection of the fuel rail area. My focus will be on the fuel pressure regulator and the vacuum source for the fuel pressure regulator (if applicable). I would check the regulator for leaks. If there is gas inside or outside the regulator, suspect that it is out of order.

If there are no obvious mechanical problems in the engine compartment, several tools will be required to proceed with the diagnosis:

1. Diagnostic Scanner
2. Digital Volt / Ohmmeter (DVOM)
3. Fuel pressure gauge with adapters
4. Reliable source of vehicle information

Then I would connect the scanner to the car diagnostic port. I retrieved all the stored codes and freeze frame data and then wrote it all down for future reference. Now I would clear the codes and test drive the car to see if any are reset.

Access the scanner data stream and observe the oxygen sensor performance to see if a rich exhaust condition actually exists. I like to narrow down the data stream to include only the relevant data. This provides faster data response times and more accurate readings.

If an actual rich exhaust condition is present:

Step 1

Use a pressure gauge to check the fuel pressure and compare it with the manufacturer's data. If the fuel pressure is within specification, go to step 2. If the fuel pressure is higher than the maximum specifications, use the DVOM to test the fuel pressure regulator circuits as well as the regulator itself (if electronic). Disconnect all related controllers from the circuit before using the DVOM to test resistance and / or continuity with the DVOM. Failure to disconnect the controller may damage it.

Repair or replace system circuits or components that do not meet manufacturer's specifications. If the fuel pressure regulator is operated by the engine vacuum, it should be replaced if the fuel pressure is too high.

Step 2

Access the injector connector (for the injector in question) and use the DVOM (or noid lamp if present) to check the injector voltage and ground pulse (the last of the PCM). If no ground pulse is detected at the injector connector, or if ground is permanent (engine running), go to step 3.

If voltage and ground impulse are present, reconnect the injector, use a stethoscope (or other listening device) and listen with the engine running. The audible clicking sound should be repeated at regular intervals. If there is no sound or it is intermittent, suspect that the injector of the corresponding cylinder is out of order or clogged. Any condition is likely to require an injector replacement.

Step 3

Most modern fuel injection systems provide a constant supply of battery voltage to each fuel injector, with the PCM delivering a ground pulse at the appropriate time to close the circuit and cause fuel to spray into the cylinder. Use DVOM to check injector pulse on PCM connector. If there is no ground (or permanent ground) pulse on the PCM connector, and no other codes are present, suspect a faulty PCM or a PCM programming error.

Note. Use caution when checking / replacing high pressure fuel system components.

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