Worn or faulty spark plug on cylinder 11; Failed ignition coil or coil connector on cylinder 11; Faulty or blocked fuel injector on cylinder 11, or its wiring; Vacuum or intake leak near cylinder 11 or a faulty intake manifold gasket; Low compression on cylinder 11 (valve, piston ring or head gasket fault); Wiring or connector fault between the control unit and the cylinder 11 ignition or injector circuit; Fuel quality problem or fuel delivery fault affecting that bank.

P0311

Cylinder 11 Misfire Detected.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
3: AreaIgnition system or misfire
11: FaultThe specific fault in that area

What it means

P0311 means the engine control unit has detected misfiring on cylinder 11, which is only found on engines with at least 11 cylinders (such as V12 engines). It sets when crankshaft speed monitoring shows that cylinder is not contributing its expected power over a number of engine cycles. Cylinder numbering and layout depend on the manufacturer and engine, so confirm which physical cylinder is number 11 before testing.

Symptoms

Engine misfiring, rough running or shaking at idle
Flashing or steady engine warning light
Loss of power and poor acceleration
Hesitation or juddering under load
Fuel smell or raised fuel consumption
Possible additional misfire codes for other cylinders

Possible causes

Worn or faulty spark plug on cylinder 11likely
Failed ignition coil or coil connector on cylinder 11likely
Faulty or blocked fuel injector on cylinder 11, or its wiringpossible
Vacuum or intake leak near cylinder 11 or a faulty intake manifold gasketpossible
Low compression on cylinder 11 (valve, piston ring or head gasket fault)rare
Wiring or connector fault between the control unit and the cylinder 11 ignition or injector circuitpossible
Fuel quality problem or fuel delivery fault affecting that bankrare

How to diagnose

Read all stored and pending codes and the freeze frame data (engine speed, load, temperature) to see when the misfire occurs.
Confirm from the manufacturer's data which physical cylinder is number 11 on this engine, and check for other misfire codes on the same bank.
Inspect the ignition coil, plug connector, injector connector and wiring for cylinder 11 for damage, oil contamination or corrosion.
Remove and inspect the spark plug for wear, fouling or damage, and compare it with the other plugs.
Swap the coil (and then plug) with a good cylinder, clear the codes and see whether the misfire follows the part.
Test injector operation and resistance on cylinder 11 and check its drive signal.
Check for intake and vacuum leaks and review fuel trims for the affected bank.
If the misfire stays after ignition and fuel checks, carry out compression and leak-down tests on cylinder 11.

How to fix

Replace the worn spark plug on cylinder 11, and the others if they are due, using the specified type.
Replace the faulty ignition coil on cylinder 11.
Clean or replace the faulty fuel injector, or repair its wiring and connector.
Repair intake or vacuum leaks and replace faulty gaskets or hoses.
Repair damaged wiring or terminals in the affected circuit.
Carry out the necessary mechanical engine repair if compression testing shows a fault.

Can I keep driving?

High severity

Avoid driving while the engine light is flashing or the engine is misfiring badly, as unburnt fuel can overheat and damage the catalytic converter. If it is only a mild misfire, drive gently and only as far as needed to get it repaired.

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