P0340 – Camshaft Position Sensor Circuit Malfunction

What does P0340 mean?

The camshaft position sensor circuit is malfunctioning. This sensor tells the computer the camshaft's position so it can time fuel injection and ignition correctly and identify which cylinder is on its compression stroke.

What causes P0340?

Listed from most to least common:

1. 1Failed camshaft position sensor
2. 2Damaged wiring or corroded connector
3. 3Oil contamination on the sensor from a leaking seal
4. 4Damaged timing components or reluctor ring
5. 5Timing chain stretch changing sensor timing relationships
6. 6Failing sensor that only misbehaves when hot

Code breakdown

Common symptoms

• Check engine light on
• Hard starting or extended cranking
• Engine stalls unexpectedly
• Rough running and misfires
• Reduced power
• In some cases, no-start

How to diagnose

1. 1Inspect the sensor and connector for oil contamination, which is very common when a nearby seal leaks.
2. 2Check wiring for damage or chafing.
3. 3Verify the sensor signal with a scan tool or oscilloscope while cranking.
4. 4Measure resistance against specification where applicable.
5. 5Check for related timing codes such as P0016 that would indicate a mechanical timing problem rather than a sensor fault.
6. 6Test when hot if the fault is intermittent.

Can cause hard starting, stalling, or a no-start condition. On vehicles with variable valve timing it also disrupts VVT operation.

Common fixes and estimated costs

Costs are rough US estimates including parts and labor. Actual pricing varies significantly by vehicle, region, and shop rates.

Good to know

Oil leaking onto the sensor is a frequently overlooked cause. If you find the sensor soaked in oil, replacing it without fixing the leaking seal means the new sensor will fail the same way.

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