P03C7
Cylinder 6 Pressure Sensor Circuit.
- 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
- C7
- FaultThe specific fault in that area
What it means
P03C7 is a generic code meaning the engine control unit has detected a fault in the cylinder 6 pressure sensor circuit. This sensor measures combustion pressure inside the cylinder, and the control unit sets the code when the signal is missing, out of range, implausible or stuck. The exact fault limits and the way the sensor is fitted vary by manufacturer and engine.
Symptoms
- Engine warning light on
- Rough running or misfire on cylinder 6
- Reduced power or the engine running in a limited mode
- Poor fuel economy
- Rough idle or uneven running under load
- Other cylinder pressure sensor codes stored alongside
Possible causes
- Damaged, chafed or corroded wiring to the cylinder 6 pressure sensor (open circuit, short to earth or short to supply)likely
- Poor connection at the sensor plug or control unit connector, such as corrosion, bent pins or loose terminalslikely
- Faulty cylinder 6 pressure sensorpossible
- Sensor contaminated by carbon or oil deposits, or damaged by heat or a combustion problem in cylinder 6possible
- Problem with the sensor supply or reference voltage or earth shared with other sensorspossible
- Faulty engine control unit or its internal sensor input circuitrare
- Outdated or faulty control unit software where the manufacturer has published a fixrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting engine load, speed and temperature when the fault set, and check for other cylinder pressure sensor or misfire codes.
- Check for relevant manufacturer technical bulletins or software updates for the vehicle and engine.
- Inspect the wiring and connector for the cylinder 6 sensor for chafing, heat damage, oil contamination, corrosion, water ingress and bent or pushed-back pins.
- Clear the code and check whether it returns straight away (a hard circuit fault) or only under certain conditions (an intermittent fault). Wiggle the harness while watching live data.
- Compare live cylinder 6 pressure sensor readings with the other cylinders at idle and under load, looking for a flat, missing or erratic signal.
- Measure the sensor supply voltage, earth and signal wire for continuity and shorts, following the manufacturer's wiring diagram for the engine.
- Check cylinder 6 mechanical condition if readings are implausible, for example with a compression or leak-down test and a look at the injector and spark plug or glow plug.
- If the wiring and supply are sound, test or swap in a known good sensor following the manufacturer's procedure, then retest.
How to fix
- Repair or replace damaged wiring and clean or replace corroded or damaged connector terminals.
- Replace the cylinder 6 pressure sensor if it fails testing, following the manufacturer's torque and fitting procedure.
- Correct any supply or earth fault affecting the sensor circuit.
- Repair any underlying cylinder 6 combustion or mechanical fault that has damaged or contaminated the sensor.
- Update the control unit software only if a manufacturer bulletin lists it as a fix for this fault.
- Replace or repair the engine control unit only after all other causes have been ruled out.
Can I keep driving?
Medium severity
The car can usually be driven short distances, but the control unit may be unable to manage combustion on that cylinder accurately. Get it diagnosed soon, and stop driving if it runs roughly, misfires heavily or loses power.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.