Cylinder 6 pressure sensor, its wiring or its connector faulty (on engines fitted with one); Weak or intermittent combustion in cylinder 6 from an ignition fault such as a worn spark plug or failing coil (petrol engines); Cylinder 6 fuel injector leaking, clogged or under-delivering; Low compression in cylinder 6 from valve, piston ring or head gasket damage; Valve timing or variable valve actuation fault affecting cylinder 6; Outdated or faulty control unit calibration or an internal control unit fault.

P03CE

Cylinder 6 Pressure Variation Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

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

What it means

P03CE means the engine control unit has judged the combustion pressure variation in cylinder 6 to be lower than expected. The exact way it measures this depends on the engine. It may use a dedicated in-cylinder pressure sensor or estimate pressure from other signals. Either the cylinder is not producing normal combustion pressure, or the signal used to measure it is faulty.

Symptoms

Engine management light on
Rough running or uneven idle
Loss of power or flat spots under load
Misfire codes or misfire counts on cylinder 6
Increased fuel consumption
Possible reduced-power or limp mode, depending on the model

Possible causes

Cylinder 6 pressure sensor, its wiring or its connector faulty (on engines fitted with one)likely
Weak or intermittent combustion in cylinder 6 from an ignition fault such as a worn spark plug or failing coil (petrol engines)likely
Cylinder 6 fuel injector leaking, clogged or under-deliveringpossible
Low compression in cylinder 6 from valve, piston ring or head gasket damagepossible
Valve timing or variable valve actuation fault affecting cylinder 6rare
Outdated or faulty control unit calibration or an internal control unit faultrare

How to diagnose

Read all stored and pending codes and the freeze frame data. Note engine load, speed and temperature when the code set, and look for related misfire, injector or sensor codes.
Visually inspect the cylinder 6 sensor wiring (if fitted), connectors, coil connector and injector connector for damage, corrosion, chafing and loose pins.
Check live misfire counters and fuel trims for cylinder 6 compared with the other cylinders.
Inspect the cylinder 6 spark plug and coil, or check injector operation, and compare with a neighbouring cylinder. Swapping parts between cylinders can show whether the fault follows the part.
Check the sensor signal and its supply and ground against the manufacturer's data, if the engine has an in-cylinder pressure sensor.
Perform a compression or leak-down test on cylinder 6 and compare it with the other cylinders.
Check for manufacturer service information or calibration updates for this model and engine, as the diagnosis varies between engines.
Clear the code and road test, then recheck for the code returning under the same conditions.

How to fix

Repair or replace damaged wiring or connectors on the cylinder 6 circuit.
Replace a faulty cylinder 6 pressure sensor, if fitted, once the wiring and supply have been proven good.
Replace worn spark plugs or a failing ignition coil on cylinder 6.
Clean or replace a faulty cylinder 6 injector.
Carry out the mechanical repair indicated by the compression or leak-down results, such as valve, piston ring or head gasket work.
Apply an official control unit calibration update only where one is documented for this fault.

Can I keep driving?

Medium severity

Short, gentle journeys are usually possible, but get it checked soon. A continuing weak or misfiring cylinder can overheat the catalytic converter and cause further engine damage. If the engine runs very roughly, the warning light flashes or power is greatly reduced, stop driving and seek assistance.

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