P0340: Camshaft Position Sensor Circuit Malfunction

P0340 is the Camshaft Position Sensor Circuit Malfunction code: the engine computer is not getting a valid signal from the camshaft position (CMP) sensor, which it needs to time fuel injection and ignition to the right cylinder. The most common cause is a failed CMP sensor itself. Typical symptoms are hard starting, no-start, or sudden stalling. A replacement sensor and labour usually runs about 40 to 180 euros.

P0340 is a ignition-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P0340 and illuminates the check engine light.

If your vehicle has triggered P0340, you may notice one or more of these symptoms:

• Check engine light illuminated
• Engine cranks but will not start (no-start condition)
• Sudden or intermittent stalling while driving
• Hard starting, especially when the engine is warm
• Rough idle, hesitation, or misfires
• Noticeable loss of power or surging under acceleration
• Engine may enter reduced-power limp mode in some vehicles

Here are the most common causes of P0340, ranked by how likely they are to be the culprit:

No - address this immediately. May cause no-start, stalling, or intermittent shutdown. If the engine starts and runs, drive only short distances to a shop. If it stalls unpredictably, do not drive. Have it towed.

Follow these steps to pinpoint the root cause of P0340:

1. Scan for companion codes (P0016, P0341, P0345). P0016 alongside P0340 points toward timing chain or cam timing issues rather than a simple sensor failure
2. Inspect the CMP sensor connector and tip for oil contamination, corrosion, bent pins, or a loose lock tab
3. Check the sensor harness for chafed, melted, or broken wires between the connector and the ECU, and wiggle-test for an intermittent fault
4. With the key on and engine off, confirm sensor supply voltage (typically 5V or 12V) and a good ground at the connector
5. Measure sensor resistance with a multimeter on magnetic types and compare to the manufacturer spec (often 200-2000 ohms); Hall-effect types are tested by watching the signal on a scope or scan tool while cranking
6. Inspect the sensor mounting and the reluctor (tone) ring on the camshaft for looseness, damage, or debris that would distort the signal
7. If the sensor, wiring, and reluctor ring all test good, check timing chain stretch and cam timing as the root cause

Repair costs for P0340 vary depending on the root cause and your vehicle. Here are typical estimates:

P0340 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:

These codes are often seen alongside P0340 or indicate related issues: