Fuel and air

P02AE — Cylinder 6 Fuel Trim at Maximum Limit

Severity: medium Drive with care, to a shop

What P02AE means

P02AE means the engine control unit can no longer correct the air-fuel mixture in cylinder 6, because the fuel trim has hit its maximum allowed limit. Normally the ECU adjusts injector pulse time based on oxygen sensor feedback, but with a large lean or rich deviation there is no correction range left. This code appears on engines that use per-cylinder fuel trim.

Symptoms

  • Check Engine light on
  • Rough or unstable idle
  • Loss of power or hesitation when accelerating
  • Worse fuel economy
  • Misfires or engine shaking
  • Higher emissions

Possible causes

  1. Faulty or clogged fuel injector on cylinder 6
  2. Vacuum or intake air leak near cylinder 6 (gasket, hose, vacuum line)
  3. Faulty oxygen, MAF or MAP sensor
  4. Low fuel pressure (pump, regulator, filter)
  5. Ignition problems (spark plug, coil) or a mechanical fault in the cylinder
  6. Wiring or connector fault at the injector
  7. Exhaust leak ahead of the oxygen sensor

How to diagnose

  1. Scan all codes and freeze frame data, and look for related mixture or misfire codes
  2. Watch short-term and long-term fuel trims at idle and under load
  3. Inspect the intake tract, hoses and vacuum lines for leaks, using a smoke machine if needed
  4. Check the cylinder 6 injector connector and wiring, and measure injector resistance
  5. Compare cylinder balance: injector balance test and misfire counts
  6. Measure fuel pressure and check that it holds after shutoff
  7. Inspect the cylinder 6 spark plug and coil, and swap with a neighbor to see if the problem moves
  8. Check compression and the MAF and oxygen sensor readings

Common fixes

  • Clean or replace the cylinder 6 fuel injector
  • Fix the air leak: replace the intake manifold gasket or hoses
  • Replace a faulty oxygen, MAF or MAP sensor
  • Repair the fuel supply: pump, pressure regulator or filter
  • Replace the spark plug or coil, or repair the mechanical engine fault
  • Repair the injector wiring or connector

Questions and answers

What does P02AE mean?

The ECU can't correct the air-fuel mixture in cylinder 6 because fuel trim has reached its limit. A bad injector or an air leak is the most common cause.

Can I drive with P02AE?

Briefly, yes, but don't put it off. Driving long with a lean mixture or misfires can damage the catalytic converter and the engine.

Will clearing the code fix it?

No. If the cause remains, the code will return. Check fuel trims, the injector and the intake system first.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.