What it means
A general electrical fault on the cylinder 7 combustion pressure sensor — used on engines with closed-loop combustion control (e.g. some Volvo and BMW direct-injection diesels) to measure cylinder pressure directly via a sensor at the glow plug or injector position.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The cylinder 7 pressure sensor measures combustion pressure for the controller's cylinder-by-cylinder combustion checks. This general circuit code sets when the controller detects an electrical fault in the cylinder 7 sensor circuit, which can involve the sensor, wiring, supply, or ground.
Common causes
Most likely first.
- Cylinder 7 pressure sensor failure
- Damaged or corroded sensor connector
- Open or shorted sensor wiring
- Fault in the sensor supply or ground circuit
Symptoms
- Check-engine light
- Rough or uneven engine running
- Misfire or hesitation
- Reduced engine power
How to diagnose it
- Save freeze-frame data and check live data for the cylinder 7 pressure reading and any related sensor-circuit codes.
- Inspect the cylinder 7 sensor connector and harness for corrosion, loose or pushed-back terminals, chafing, or damage.
- Use the wiring diagram to check the cylinder 7 sensor supply and ground against the manufacturer's specification.
- Check the signal wire for an open or short and verify connector terminal fit.
- If the circuit checks pass, test the cylinder 7 pressure sensor using the manufacturer's procedure.
Common fixes
- Repair damaged or chafed cylinder 7 sensor wiring.
- Clean or repair corroded, loose, or pushed-back connector terminals.
- Restore a failed sensor supply or ground connection.
- Replace the cylinder 7 pressure sensor if it fails testing.
Can I keep driving?
If the engine runs normally and only the check-engine light is on, gentle driving to arrange diagnosis is generally reasonable. Reduce load or stop if rough running, misfire, or power loss appears because the controller may have lost reliable cylinder 7 pressure data.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.