P02BF
Cylinder 10 - Fuel Trim at Min Limit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 2
- AreaFuel and air metering (injector circuit)
- BF
- FaultThe specific fault in that area
What it means
P02BF means the engine control unit has reached the minimum limit of its individual fuel correction for cylinder 10, so it cannot take away any more fuel from that cylinder. It saw that cylinder running richer than the target air-fuel ratio, or the engine's balance data suggested too much fuel, and the correction ran out of range. This code only applies to engines with ten or more cylinders, and which physical cylinder is number 10 depends on the engine.
Symptoms
- Check engine light on
- Rough or uneven idle
- Smell of unburnt fuel or black smoke from the exhaust
- Higher than normal fuel consumption
- Hesitation or poor smoothness under light load
- Possible additional misfire or other fuel trim codes stored
Possible causes
- Leaking, dripping or stuck-open fuel injector on cylinder 10likely
- Injector electrical fault on cylinder 10 (wiring, connector or injector coil) causing incorrect fuellingpossible
- Oxygen or air-fuel ratio sensor serving that cylinder's bank reading falsely rich, or contaminatedpossible
- Fuel pressure too high on that bank or fuel rail (faulty regulator or pressure control, where fitted)possible
- Intake air or manifold fault affecting cylinder 10, such as a restricted intake runner or a faulty airflow readingrare
- Ignition fault on cylinder 10 or cylinder wear giving poor combustion and distorted exhaust readingsrare
- Outdated or faulty engine control unit calibration, where the manufacturer has issued a fix for this coderare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting any other cylinder trim, misfire, fuel pressure or sensor codes.
- Check live data for fuel trims on each bank and, if available, each cylinder, to see whether the fault is limited to cylinder 10 or affects the whole bank.
- Confirm which physical cylinder is number 10 for this engine using the manufacturer's information before working on any parts.
- Inspect the injector wiring, connector and earth for cylinder 10 for damage, corrosion, water or loose pins.
- Check the spark plug for cylinder 10 for sooting or fuel wetting and compare it with the others.
- Check fuel pressure and look at fuel pressure live data against the specification for that engine.
- Test the injector for cylinder 10 for resistance, flow and leakage, comparing it with the other injectors, following the procedure for that engine.
- Check the relevant air-fuel ratio or oxygen sensor signal and response, and check for any available calibration updates for this code.
How to fix
- Replace or professionally clean and flow-test a leaking or faulty injector on cylinder 10.
- Repair damaged wiring, connectors or earths in the cylinder 10 injector circuit.
- Replace a faulty or contaminated air-fuel ratio or oxygen sensor once the cause of contamination is found.
- Repair the fuel pressure control fault so that pressure matches the specification.
- Clear any intake restriction on cylinder 10 and repair any ignition or mechanical fault found.
- Apply a manufacturer calibration update only if the checks show a known software cause.
Can I keep driving?
The car can usually be driven for a short time, but a rich cylinder can wash oil from the bore, foul plugs and overload the catalytic converter. Have it checked soon and avoid heavy loads or long journeys until it is fixed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.