Cylinder 2 pressure sensor internal fault giving a high signal; Wiring short to supply voltage in the sensor signal circuit; Damaged, corroded or loose connector at the sensor or control unit; Open circuit or high resistance in the sensor ground return, pulling the signal high; Sensor supply voltage fault or related circuit shared with other cylinder sensors; Fault inside the engine control unit or its sensor input stage.

P03A2

Cylinder 2 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
A2: FaultThe specific fault in that area

What it means

P03A2 means the engine control unit has detected a high voltage or signal level in the circuit of the cylinder 2 pressure sensor, which measures combustion pressure inside that cylinder. The signal sat above the expected range for longer than the strategy allows, pointing to a short to voltage, a sensor fault or a control unit fault. Cylinder pressure sensors are only fitted to certain engines, so the exact layout depends on the model.

Symptoms

Engine warning light on
Rough running or misfire-like hesitation on cylinder 2
Poor combustion control, reduced power or economy
Increased exhaust smoke or rough idle on some engines
Engine may enter a reduced-performance (limp) mode

Possible causes

Cylinder 2 pressure sensor internal fault giving a high signallikely
Wiring short to supply voltage in the sensor signal circuitlikely
Damaged, corroded or loose connector at the sensor or control unitpossible
Open circuit or high resistance in the sensor ground return, pulling the signal highpossible
Sensor supply voltage fault or related circuit shared with other cylinder sensorspossible
Fault inside the engine control unit or its sensor input stagerare

How to diagnose

Read all stored codes and freeze frame data, noting whether other cylinder pressure sensor codes are present
Check for technical service bulletins or known issues for the specific engine, as fitment and design vary by model
Visually inspect the cylinder 2 sensor wiring and connector for chafing, heat damage, oil contamination, corrosion and bent or pushed-back pins
Check live data for the cylinder 2 pressure signal against the other cylinders with the engine off and then running
Check the sensor supply voltage and ground at the connector against the manufacturer's wiring diagram
Test the signal wire for a short to voltage and for continuity back to the control unit with the circuit disconnected
Swap-test or substitute a known good sensor only where the manufacturer permits, then recheck the live data
Clear the code and road test to see if it returns immediately or only under load

How to fix

Replace the cylinder 2 pressure sensor if it is faulty, following the manufacturer's torque and fitting procedure
Repair or replace damaged wiring that is shorted to voltage
Clean or replace corroded or damaged connectors and terminals
Restore the ground connection or repair the supply circuit fault
Replace or repair the engine control unit only after all wiring and sensor causes are ruled out, and have it programmed as required

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, but get it checked soon as combustion control may be degraded and the fault could worsen. If the engine runs roughly, loses power or flashes the warning light, stop driving and have it inspected.

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