What does P02A6 Cylinder 4 Fuel Trim at Max Limit mean?
The P02A6 OBD code refers to a specific engine cylinder, in this case cylinder #4, experiencing an extremely lean condition.
The powertrain control module (PCM) uses the fuel trim system to adjust fuel delivery based on input signals from the oxygen sensors.
Short term fuel trim is constantly calculated by the PCM and can vary within a broad range.
However, when the fuel trim exceeds the maximum threshold, a code of this type is stored.
This code is classified as severe because a lean fuel condition can cause significant engine damage.
Symptoms may include diminished engine performance, delayed engine startup, and stored lean exhaust codes.
Common causes for this code include defective/leaking fuel injectors, a bad fuel pump, engine vacuum leaks, and faulty oxygen sensors.
Troubleshooting steps may include checking for vacuum leaks, inspecting the fuel injector for signs of failure, and using diagnostic tools like a scanner and fuel pressure gauge to determine the cause of the lean condition.
P02A6 Symptoms
- Diminished engine performance
- Delayed engine startup
- Presence of stored lean exhaust codes
- Misfire codes may also be stored
Possible P02A6 Causes
- Defective/leaking fuel injector
- Bad fuel pump
- Engine vacuum leak (including EGR valve failure)
- Faulty oxygen sensor
- Mass air flow (MAF) or Manifold Air Pressure (MAP) sensor failure
Troubleshooting P02A6 error code
- Diagnose and repair MAF or MAP related codes
- Inspect engine intake manifold area for vacuum leaks
- Check hoses and plastic lines for cracking or collapse
- Inspect PCV lines for vacuum leaks
- Check edges of the intake for signs of gasket failure
- Examine fuel injector for signs of fuel leakage
- Connect a diagnostic scanner and retrieve stored codes and freeze frame data
- Clear codes and test-drive the vehicle to see if any are reset
- Observe oxygen sensor operation in the data stream to confirm lean exhaust condition
- Test fuel pressure using a fuel pressure gauge
- If fuel pressure is below specs, test fuel pump relay and voltage
- If fuel pressure is within specs, proceed to next step
- Test injector voltage and ground pulse at the injector connector
- Listen to the injector for an audible clicking sound
- If no voltage at the injector connector, proceed to next step
- Test system fuses and relays for battery voltage
- Replace fuses and relays as needed
- Trace the circuit using vehicle information source and make necessary repairs
