Camshaft Position Sensor Warning: Timing and Performance Issues
Updated: February 2026
The camshaft position sensor (CMP) warning triggers the check engine light with camshaft sensor codes (P0340-P0349). This sensor monitors camshaft position and speed, working with the crankshaft sensor to ensure precise timing of valve operation and fuel injection in modern engines.
CMP vs. CKP Sensors
While the crankshaft sensor tracks piston position, the camshaft sensor tracks valve position. The engine computer uses both sensors together to determine exactly which cylinder is on its power stroke, ensuring fuel is injected and spark occurs at precisely the right moment for each cylinder.
Symptoms of Sensor Problems
- Hard starting or extended cranking before engine starts
- Check engine light with camshaft sensor codes
- Rough idle or engine misfires
- Poor acceleration and reduced power
- Engine stalling at idle or when decelerating
- Increased fuel consumption
- In some vehicles: complete no-start condition
Common Failure Causes
Similar to crankshaft sensors, heat and vibration cause most failures. Oil leaks that contaminate the sensor or its connector are common, especially on engines where the sensor is exposed to engine oil . Timing chain or belt wear can affect sensor readings even if the sensor itself is functional.
Diagnosis and Repair
Professional diagnosis is necessary to determine if the sensor, wiring, or actual timing components are at fault. Sensor replacement costs $100-$400 depending on location and accessibility. Some engines have multiple camshaft sensors (one per bank or per camshaft in dual overhead cam engines), and codes will indicate which sensor requires replacement.
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Frequently Asked Questions about Camshaft Position Sensor Warning: Timing and Performance Issues
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