Diagnostic Trouble Code

P0343

Camshaft Position Sensor "A" Circuit High — Bank 1 / Single Sensor

What the code means

The ECU is seeing a camshaft-position signal or circuit condition that is higher than expected.

P0343 is generally described as Camshaft Position Sensor "A" Circuit High. It tells us there is a problem with the camshaft-position signal or its electrical circuit — it does not automatically tell us that the sensor itself has failed.

The ECU relies on the camshaft-position sensor and the mechanical target it reads to determine camshaft position. A perfectly good sensor cannot produce a correct signal if the target or pickup arrangement is damaged or incorrectly positioned.

The Speed Tweaks video on this page follows a Mini R56 with the N16 engine, presenting with P0343 together with Mini/BMW fault 2982 and cutting-out or non-start symptoms. In that particular case, the underlying problem was the pickup ring on the camshaft.

Possible causes

What could cause P0343?

Camshaft position sensor fault

Sensor power-supply or ground problem

Signal wire shorted high or other wiring fault

Poor, damaged or contaminated connector

Damaged or incorrectly positioned camshaft pickup/trigger ring

Mechanical camshaft or timing-related problem

Incorrect sensor-to-target relationship

ECU input or other circuit fault

Diagnostic approach

What should you check?

1. Read the complete fault memory. Check for accompanying camshaft, crankshaft, timing, synchronization or manufacturer-specific faults. On the Mini R56 case shown in the Speed Tweaks video, P0343 appeared alongside fault 2982.
2. Don't condemn the sensor from the code alone. P0343 describes a circuit or signal condition. Establish whether the sensor itself, its electrical circuit or the mechanical target being measured is responsible.
3. Check the sensor circuit. Verify the appropriate power supply, ground and signal circuit using suitable test equipment and vehicle information.
4. Check whether the signal makes sense. Where appropriate, observe the camshaft-position signal and establish whether it is switching or changing correctly rather than relying only on a static voltage measurement.
5. Remember what the sensor is looking at. If the electrical checks do not explain the fault, inspect or verify the mechanical pickup or trigger arrangement. Damage or movement of the target can produce an incorrect signal even when the sensor itself is working.
6. Consider mechanical timing and synchronization. Where symptoms or accompanying faults suggest it, verify the mechanical relationship between the crankshaft and camshaft rather than treating P0343 purely as an electrical problem.
7. Confirm the repair. After correcting the fault, confirm reliable starting and running, verify the camshaft signal or synchronization as appropriate and make sure the fault does not return.

Speed Tweaks diagnostic video

Watch the P0343 diagnostic process

Watch the Speed Tweaks workshop guide to diagnosing P0343.

Watch on YouTube →

A useful thing to remember

A sensor fault code does not always mean the sensor is faulty. The sensor, its wiring and the physical thing being measured all form part of the diagnostic picture.