P0344Powertrain
Powertrain · SAE
CMP Sensor — Intermittent
Meaning
The engine control module has detected that the camshaft position (CMP) sensor signal disappears and reappears irregularly during engine operation. The intermittent signal loss can compromise sequential injection synchronization and cause engine instability.
Common causes
- Loose, corroded, or intermittent CMP sensor connector
- Wiring harness with partial or intermittent break (flex point)
- Camshaft reluctor wheel with localized deposits periodically interrupting the signal
- CMP sensor with internal intermittent failure (temperature or vibration sensitive)
- Intermittent sensor ground fault
- Sporadic electromagnetic interference from adjacent circuits
Symptoms
- Check-engine light (MIL) on intermittently
- Sporadic misfires or power loss while driving
- Engine switches intermittently between sequential and batch injection
- Appearing and disappearing idle instability
- Fault may be difficult to reproduce in the workshop
Severity
Moderate to high: intermittent CMP signal losses reduce performance and may cause drivability irregularities; tend to worsen over time.
What to do
- Wiggle wiring and connector during live-data monitoring to reproduce the fault
- Inspect the CMP sensor connector for loose pins, corrosion, or moisture ingress
- Check the harness along its route for chafe points or kinks
- Clean the camshaft reluctor wheel of any deposits
- Replace the CMP sensor and connector if the fault is confirmed