Faulty or leaking fuel injector on cylinder 8 (clogged, stuck or over-fuelling); Vacuum or intake air leak affecting cylinder 8 only, such as a cracked intake manifold runner or a worn seal at that port; Wiring or connector fault at the cylinder 8 injector (high resistance, corrosion, damaged loom); Mechanical problem on cylinder 8, such as low compression, a burnt valve or a worn valve seal affecting combustion; Ignition fault on cylinder 8, such as a weak coil or worn spark plug, leaving unburnt mixture that the ECU misreads; Exhaust leak near the cylinder 8 oxygen sensor, or a faulty sensor on that bank, giving false readings; Outdated or faulty ECU calibration, where the manufacturer has issued an update for this fault.

P02B6

Cylinder 8 - Fuel Trim at Max 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)
B6: FaultThe specific fault in that area

What it means

P02B6 means the engine control unit has seen the fuel trim correction for cylinder 8 reach its maximum limit. The ECU is trying to correct the air-fuel mixture for that cylinder individually, by adding or removing fuel, but cannot correct it any further. This points to a problem specific to cylinder 8 and not a general fault across the whole engine.

Symptoms

Engine warning light on
Rough idle or misfire-like shake
Hesitation or poor pickup under load
Increased fuel consumption
Smell of fuel or a lean, surging idle
Possible additional misfire or fuel trim codes stored

Possible causes

Faulty or leaking fuel injector on cylinder 8 (clogged, stuck or over-fuelling)likely
Vacuum or intake air leak affecting cylinder 8 only, such as a cracked intake manifold runner or a worn seal at that portlikely
Wiring or connector fault at the cylinder 8 injector (high resistance, corrosion, damaged loom)possible
Mechanical problem on cylinder 8, such as low compression, a burnt valve or a worn valve seal affecting combustionpossible
Ignition fault on cylinder 8, such as a weak coil or worn spark plug, leaving unburnt mixture that the ECU misreadspossible
Exhaust leak near the cylinder 8 oxygen sensor, or a faulty sensor on that bank, giving false readingsrare
Outdated or faulty ECU calibration, where the manufacturer has issued an update for this faultrare

How to diagnose

Read all stored codes and freeze frame data, noting engine load, temperature and fuel trim values when the code set, and check for misfire or other fuel trim codes
Visually inspect the cylinder 8 injector connector, wiring and nearby loom for damage, corrosion or heat damage
Inspect the intake manifold, gaskets, vacuum hoses and seals around cylinder 8 for leaks, using a smoke test if needed
Check live data for fuel trims and misfire counters, and compare cylinder 8 with the other cylinders
Test the cylinder 8 injector for correct electrical resistance and operation, and compare against the other injectors
Swap the ignition coil and spark plug from cylinder 8 with another cylinder and see if the fault follows
Carry out a compression and leak-down test on cylinder 8 if the fuel and air checks pass
Check for a manufacturer calibration update or technical bulletin relevant to this engine, as procedures vary by model

How to fix

Clean or replace the faulty cylinder 8 injector as testing dictates
Repair or replace damaged wiring or connectors at the injector
Replace leaking intake manifold gaskets, seals or cracked components on cylinder 8
Replace the faulty ignition coil or spark plug on cylinder 8
Repair internal engine faults on cylinder 8, such as valve or seal wear, if compression tests confirm them
Apply a manufacturer calibration update if one is known to address this fault

Can I keep driving?

Medium severity

The car can usually be driven gently for a short time, but get it checked soon. Prolonged running with a badly rich or lean cylinder can cause misfires, catalytic converter damage and engine wear, so stop driving if it runs very roughly or the warning light flashes.

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