P0296
Cylinder 12 Contribution/Balance.
- 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)
- 96
- FaultThe specific fault in that area
What it means
P0296 is the generic code for a cylinder 12 contribution or balance fault. The engine control unit compares how much each cylinder contributes to engine speed and found cylinder 12 weaker than the others by more than the permitted amount. This is only seen on twelve-cylinder engines, and the cause could be ignition, fuel, air or mechanical, depending on the engine.
Symptoms
- Engine misfire or rough running, especially at idle
- Loss of power and hesitant acceleration
- Malfunction indicator lamp on, possibly flashing under load
- Increased fuel consumption
- Uneven or shaky idle with vibration
- Possible fuel smell or raw exhaust smell
Possible causes
- Faulty spark plug or ignition coil on cylinder 12likely
- Faulty or clogged fuel injector on cylinder 12likely
- Damaged wiring or poor connector contact to the cylinder 12 injector or coilpossible
- Vacuum or intake air leak affecting cylinder 12possible
- Low compression on cylinder 12 (valve, piston ring or head gasket fault)possible
- Fault in the engine control unit driver circuit for cylinder 12rare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting load, engine speed and temperature when the fault set
- Check for other misfire or fuel trim codes, which help show whether the problem is isolated to cylinder 12 or wider
- Inspect the wiring, connectors and plug for cylinder 12 ignition and injector circuits for damage, corrosion or heat
- Inspect the spark plug on cylinder 12 for wear, fouling or damage and compare with other cylinders
- Swap the coil, or the plug, with a known good cylinder and see whether the fault follows it, using the manufacturer's procedure for your engine
- Test the cylinder 12 injector for resistance and operation, and check its spray pattern or flow as the engine design allows
- Smoke test or inspect for intake leaks near cylinder 12 and check the intake manifold seals
- Carry out a compression or leak-down test on cylinder 12 if ignition and fuel checks pass
How to fix
- Replace the faulty spark plug or ignition coil on cylinder 12, and consider replacing the plugs as a set if they are worn
- Replace or professionally clean and test the cylinder 12 fuel injector
- Repair damaged wiring or connectors in the affected circuit
- Replace leaking intake gaskets or vacuum hoses
- Carry out the necessary engine repair if compression is low, as diagnosed by the test results
Can I keep driving?
Medium severity
Short, gentle driving to a workshop is usually acceptable, but avoid heavy loads. If the warning lamp flashes, reduce load and stop driving soon, as unburnt fuel can damage the catalytic converters.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.