P02AE

Cylinder 6 - Fuel Trim at Max Limit

P02AE is a generic OBD-II powertrain diagnostic trouble code: Cylinder 6 - Fuel Trim at Max Limit. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P02AE
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P02AE means

Code P02AE is stored when the powertrain control module determines that the individual fuel trim correction applied to cylinder 6 has reached its maximum positive limit. On engines equipped with per-cylinder fuel trim monitoring — a feature common to modern direct-injection and some port-injection systems — the PCM continuously adjusts injector pulse widths to balance combustion output across all cylinders. A maximum positive trim on cylinder 6 means the PCM has added as much extra fuel as the calibration allows and still cannot achieve the target air-fuel ratio for that cylinder. This signals a lean condition localised to cylinder 6, which can arise from inadequate fuel delivery (restricted injector, low rail pressure) or from excess air entering the combustion event (vacuum leak, faulty sensor). Because the code only triggers when correction has been exhausted, by the time P02AE is set the cylinder is already operating significantly outside its target mixture. Sustained lean combustion raises combustion temperatures, risking damage to the piston crown, exhaust valves, and catalytic converter. The code applies only to engines with six or more cylinders, as cylinder 6 must physically exist in the engine layout.

Common causes

Most-frequently reported root causes when P02AE is logged.

  • 1
    Restricted or partially clogged fuel injector on cylinder 6 reducing fuel delivery
  • 2
    Vacuum or intake manifold leak near cylinder 6 introducing excess unmetered air
  • 3
    Faulty or lazy oxygen/wide-band sensor on the cylinder 6 bank skewing feedback
  • 4
    Low fuel pressure from a weak fuel pump or blocked fuel filter starving rail pressure
  • 5
    Failed or sticking EGR valve admitting excess exhaust gases to the intake near cylinder 6
  • 6
    Mass air flow (MAF) or manifold air pressure (MAP) sensor inaccuracy causing the PCM to miscalculate base fuelling
  • 7
    Injector wiring or connector fault (high resistance) reducing the electrical drive to the cylinder 6 injector
  • 8
    Minor injector O-ring air leak allowing a small vacuum path into the port

Symptoms drivers notice

MIL illuminated with P02AE stored, possibly alongside lean or misfire codes for cylinder 6
Rough idle or hesitation, especially noticeable at light throttle where trims are most active
Reduced engine power or torque, potentially triggering a limp-home mode on some calibrations
Poor fuel economy as other cylinders are over-fuelled to compensate for bank imbalance
Engine stumble or surge at cruise speeds
Possible failed emissions test due to elevated HC/NOx from lean combustion in cylinder 6

How to diagnose P02AE

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all stored codes and live fuel trim data; note both short-term and long-term trim on the cylinder 6 bank
  2. 2
    Check for intake or vacuum leaks near cylinder 6 using a smoke machine or propane enrichment method
  3. 3
    Measure fuel rail pressure at idle and under load against the manufacturer's specification
  4. 4
    Perform an injector balance test to confirm cylinder 6 is contributing less than adjacent cylinders
  5. 5
    Test the oxygen sensor on the cylinder 6 bank for sluggish or skewed response using a graphing scan tool
  6. 6
    Inspect the MAF sensor for contamination and compare its reported airflow to expected values at idle
  7. 7
    Clear the code, perform a warm road test under the conditions recorded in freeze-frame data, and recheck trims

Related powertrain codes

Frequently asked questions

Why does P02AE only appear on 6+ cylinder engines?

The code specifically references cylinder 6. On a 4-cylinder engine cylinder 6 does not exist, so the PCM would never set this code. It is exclusive to V6, inline-6, V8, and larger engine configurations.

Is P02AE a serious code?

Yes. A lean combustion condition sustained at the limit of correction raises combustion temperatures and risks damage to pistons, exhaust valves, and the catalytic converter. It should be diagnosed and repaired without delay.

Can a dirty MAF sensor cause P02AE?

Yes. If the MAF over-reports airflow, the PCM calculates more fuel than is needed globally, but when per-cylinder trims reveal cylinder 6 is still lean, P02AE can set. Cleaning or replacing the MAF is a valid diagnostic step.

What is the difference between P02AE and P02AF?

P02AE indicates the cylinder 6 fuel trim has been pushed to its maximum positive (adding fuel) limit — a lean cylinder. P02AF indicates the trim has been pushed to its maximum negative (removing fuel) limit — a rich cylinder. They represent opposite ends of the correction range.

Disabling P02AE in software

RaceTune can permanently disable P02AE — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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