Leaking or stuck-open fuel injector on cylinder 12; Faulty or contaminated oxygen or air-fuel ratio sensor on the bank containing cylinder 12; Wiring or connector fault on the cylinder 12 injector circuit, or a fault in the injector driver; Fuel pressure too high, for example a faulty regulator or pressure control fault (depends on the fuel system design); Mechanical problem on cylinder 12 such as low compression or valve sealing issues affecting combustion; Faulty ignition coil or spark plug on cylinder 12 causing incomplete combustion that the sensors read as rich; Software fault in the engine control unit where a known calibration issue exists for that engine.

P02C7

Cylinder 12 - 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)
C7: FaultThe specific fault in that area

What it means

P02C7 is a generic powertrain code meaning the fuel trim for cylinder 12 has reached its minimum limit, so the control unit is removing as much fuel as it can from that cylinder. The engine management has seen that cylinder running richer than expected, usually through individual cylinder balancing or oxygen sensor feedback, and cannot correct it any further. It only applies to engines with at least 12 cylinders, and how cylinder 12 is identified and monitored depends on the model and engine.

Symptoms

Engine management light on
Rough idle or misfire feel, especially when cold
Smell of fuel from the exhaust
Increased fuel consumption
Slight hesitation or uneven running under load
Other fuel trim or rich mixture codes stored for the same bank

Possible causes

Leaking or stuck-open fuel injector on cylinder 12likely
Faulty or contaminated oxygen or air-fuel ratio sensor on the bank containing cylinder 12possible
Wiring or connector fault on the cylinder 12 injector circuit, or a fault in the injector driverpossible
Fuel pressure too high, for example a faulty regulator or pressure control fault (depends on the fuel system design)possible
Mechanical problem on cylinder 12 such as low compression or valve sealing issues affecting combustionrare
Faulty ignition coil or spark plug on cylinder 12 causing incomplete combustion that the sensors read as richpossible
Software fault in the engine control unit where a known calibration issue exists for that enginerare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including engine temperature, load and fuel trim values
Check live fuel trim data for both banks and compare short and long term trims, looking for a rich condition on cylinder 12's bank
Inspect the cylinder 12 injector connector, wiring and earth for damage, corrosion or water ingress
Inspect the spark plug and ignition coil on cylinder 12 and compare with neighbouring cylinders
Check for fuel smell, fuel contamination of the oil and any signs of a leaking injector
Measure fuel pressure and check it against the manufacturer's specification for the engine
Test the injector electrically and for flow and leak-down, comparing it with the other cylinders
Check oxygen or air-fuel ratio sensor readings and response on the relevant bank, and check for exhaust leaks near the sensor

How to fix

Replace or professionally clean and test the faulty cylinder 12 injector
Repair damaged wiring or connectors on the injector circuit
Replace a faulty oxygen or air-fuel ratio sensor once it has been proven faulty
Correct fuel pressure faults by repairing or replacing the faulty regulator or pressure control component
Replace the worn spark plug or failed ignition coil on cylinder 12
Address any mechanical fault on cylinder 12, and apply a manufacturer calibration update only if a known software fault applies to that engine

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but a rich cylinder can wash oil from the bore and overload the catalytic converter, so have it checked soon. Stop driving if the engine misfires badly, the light flashes or you smell strong fuel.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.