Faulty cylinder 6 pressure sensor; Short to voltage or to the supply wire in the sensor signal circuit; Open circuit or high resistance in the signal or ground wire, giving a high reading; Corroded, damaged or loose connector at the sensor or control unit; Faulty or incorrect sensor reference voltage supply; Fault inside the engine control unit or the sensor signal processing module.

P03CA

Cylinder 6 Pressure Sensor Circuit High.

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
CA: FaultThe specific fault in that area

What it means

P03CA means the engine control unit has detected a high signal voltage in the circuit of the cylinder 6 pressure sensor, which measures combustion pressure inside that cylinder. The reading has gone above the expected range, which usually points to an electrical fault such as a short to voltage or an open circuit, or to a failed sensor. Fitment of cylinder pressure sensors is limited to certain engines, so the exact layout depends on the model.

Symptoms

Engine warning light on
Rough running or misfire on cylinder 6
Reduced power or the engine running in a limited-performance mode
Poor fuel economy
Uneven idle or hesitation under load

Possible causes

Faulty cylinder 6 pressure sensorlikely
Short to voltage or to the supply wire in the sensor signal circuitlikely
Open circuit or high resistance in the signal or ground wire, giving a high readingpossible
Corroded, damaged or loose connector at the sensor or control unitpossible
Faulty or incorrect sensor reference voltage supplypossible
Fault inside the engine control unit or the sensor signal processing modulerare

How to diagnose

Read all stored codes and freeze frame data, noting engine speed, load and temperature when the fault set, and check for related cylinder pressure sensor codes on other cylinders.
Clear the code and see whether it returns straight away (a hard fault) or only intermittently.
Visually inspect the cylinder 6 sensor wiring and connector for chafing, heat damage, oil contamination, bent pins and corrosion.
Check live data for the cylinder 6 pressure sensor and compare it with the other cylinders, if the engine has them, at idle and with the engine off.
With the ignition on, measure the sensor supply voltage and ground against the manufacturer's wiring diagram.
Check the signal wire for a short to voltage or an open circuit by disconnecting the sensor and measuring the signal wire to the control unit.
Wiggle-test the harness while watching live data to find intermittent faults.
If the wiring and supply are good, test or substitute the sensor following the manufacturer's procedure for that engine.

How to fix

Replace the cylinder 6 pressure sensor if it tests faulty, following the correct torque and fitting procedure for that engine.
Repair or replace damaged wiring that is shorted to voltage or open circuit in the signal circuit.
Clean, repair or replace corroded or damaged connectors and terminals.
Restore the correct reference voltage supply and ground by repairing the wiring or the fault upstream.
Have the control unit checked and, if faulty, repaired or replaced and coded as the manufacturer specifies.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but the engine may run roughly or with reduced power, and the control unit loses combustion feedback for that cylinder. Get it checked soon, and stop driving if it misfires badly or the warning light flashes.

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