What it means
A general electrical fault on the cylinder 2 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 2 pressure sensor measures combustion pressure in cylinder 2, and the engine control module uses its signal to assess that cylinder's combustion. This code indicates an electrical fault in the cylinder 2 sensor circuit, but does not by itself specify whether the problem is in the sensor, wiring, power, or ground.
Common causes
Most likely first.
- Cylinder 2 pressure sensor failure
- Damaged or corroded sensor connector
- Open or short in sensor wiring
- Fault in the sensor power or ground circuit
Symptoms
- Check engine light on
- Rough running or misfire
- Reduced engine power
- Hard starting
How to diagnose it
- Use a scan tool to save freeze-frame data and check whether cylinder 2 pressure or misfire readings changed when the fault set.
- Inspect the cylinder 2 pressure-sensor connector for corrosion, moisture, loose pins, or physical damage.
- Trace the cylinder 2 sensor harness and check for chafing, breaks, pinching, or heat damage.
- Using the wiring diagram, test the cylinder 2 sensor power, ground, and signal circuits for opens, shorts, or poor connections.
- If the wiring checks out, assess the cylinder 2 pressure sensor against the manufacturer's specification.
Common fixes
- Secure or clean the cylinder 2 pressure-sensor connector if its contacts are intact.
- Repair damaged cylinder 2 sensor wiring or connector terminals.
- Restore a faulty power or ground connection to the cylinder 2 sensor.
- Replace the cylinder 2 pressure sensor if it fails circuit or output checks.
Can I keep driving?
If the engine runs roughly or loses power, limit driving to a short, gentle trip and stop if it misfires or stalls. A cylinder 2 sensor-circuit fault can interfere with combustion control and increase emissions.
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.