P01FE
Injector Fuel Trim at Maximum Limit (Cylinder Unspecified)P01FE is a generic OBD-II powertrain diagnostic trouble code: Injector Fuel Trim at Maximum Limit (Cylinder Unspecified). 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.
What P01FE means
P01FE indicates that the PCM individual injector fuel trim correction for one or more cylinders has reached or exceeded its maximum allowable limit. Modern gasoline direct injection and diesel systems perform cylinder-individual trim corrections based on combustion feedback to balance fueling across all cylinders. When a correction value pegs at its maximum, it signals that the compensation can no longer correct the imbalance within normal limits.
The underlying cause is typically a mechanically deficient injector that is delivering significantly less or more fuel than commanded, requiring an abnormally large electronic correction. A partially clogged injector, a leaking injector, or one with a worn needle may drive the trim to its limit. Internal injector wear that alters the spray pattern or flow rate is also a common contributor.
This code may be accompanied by misfires, rough idle, or elevated emissions. In some PCM calibrations, reaching the trim limit will trigger a power reduction or limp mode to protect the catalyst and engine. Diagnosis should include injector flow testing or a comparison of individual trim values across all cylinders, with the outlier cylinder injector being the primary suspect.
Common causes
Most-frequently reported root causes when P01FE is logged.
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1
Clogged or partially blocked fuel injector reducing fuel delivery on the affected cylinder.
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2
Leaking fuel injector delivering more fuel than commanded, driving trim in the opposite direction.
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3
Worn injector needle or seat affecting flow rate and spray pattern.
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4
Low fuel pressure reducing injector flow below calibrated levels.
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5
Intake valve deposits on GDI engines affecting charge preparation and apparent fueling imbalance.
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6
Air leak on a specific cylinder causing a lean condition that drives injector trim to maximum.
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7
PCM calibration delivering incorrect base pulse widths requiring excessive trim correction.
Symptoms drivers notice
How to diagnose P01FE
A typical diagnostic flow when this code is present.
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1
Retrieve all DTCs and check for concurrent misfire codes to identify the affected cylinder.
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2
Monitor individual injector trim values with a scan tool to identify which cylinder trim is at its limit.
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3
Perform a fuel injector balance test or relative compression test to isolate the problem cylinder.
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4
Check fuel pressure and volume to rule out a low-pressure supply issue.
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5
Inspect for intake air leaks or vacuum leaks on the affected cylinder.
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6
If a GDI engine, consider intake valve carbon deposits as a contributing cause on high-mileage engines.
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7
Replace or have the suspect injector professionally flow-tested before condemning it.
Related powertrain codes
- P0100 — Mass or Volume Air Flow A Circuit Malfunction
- P0101 — Mass or Volume Air Flow A Circuit Range/Performance Problem
- P0102 — Mass or Volume Air Flow A Circuit Low Input
- P0103 — Mass or Volume Air Flow A Circuit High Input
- P0104 — Mass or Volume Air Flow A Circuit Intermittent
- P0105 — Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
Frequently asked questions
Does P01FE mean the injector must be replaced immediately?
Not necessarily immediately, but a trim at maximum limit indicates the system can no longer compensate for the imbalance. Continued operation risks catalyst damage and worsening misfire.
Can injector cleaner additives resolve this?
In mild cases of carbon fouling, a fuel system cleaner may help. However, a mechanically worn injector will not be restored by chemical cleaning.
Why do GDI engines develop injector trim issues more often?
GDI injectors spray directly into the cylinder, bypassing the intake port. Without port fuel washing the intake valves, carbon deposits accumulate and can affect charge motion and fuel distribution.
Will replacing one injector fix the problem?
If the fault is isolated to a single cylinder and the injector on that cylinder is confirmed faulty by flow testing, replacing it should resolve P01FE. Check fuel pressure first to rule out a systemic cause.
Disabling P01FE in software
RaceTune can permanently disable P01FE — 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.
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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