P0340
Camshaft Position Sensor A Circuit Bank 1 or Single Sensor
Ignition / cam-crank timing
Generic OBD-II
High
What it means
P0340 means the engine control module lost or couldn't make sense of the signal from the camshaft position sensor. That sensor tells the ECM where the camshaft is so it can time fuel injection and spark; without a reliable signal the engine can be hard to start, stall, or refuse to start at all.
High
Can I keep driving? Risky — a lost camshaft signal can cause hard starting, stalling, or a no-start, so drive as little as possible and be ready for it to quit.
Common symptoms
What you'll notice
- Check-engine light on
- Hard starting, long cranking, or intermittent no-start
- Stalling or cutting out while driving
- Misfire, hesitation, or reduced power
Common causes
Most likely first
- Failed camshaft position sensor (the most common cause)Likely
- Damaged wiring or a poor/corroded connector at the sensorCommon
- Metal debris or oil contamination on the sensor tipCommon
- Damaged reluctor/tone ring or timing chain issue affecting the signalLess often
- Failed engine control module (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check the camshaft sensor connector for oil, corrosion, or looseness.
- Inspect the sensor wiring for chafing or breaks back to the ECM.
- Test the sensor signal (and its power/ground) with the engine cranking; replace the sensor if it drops out.
- If the signal is erratic, inspect the reluctor ring and verify timing components.
- Clear the code and confirm the car starts and runs without the fault returning.
FAQ
Quick answers
Is it safe to drive with P0340?+
Not really. The engine may stall or fail to restart without warning, so treat it as urgent rather than driving on it.
Can I just clear P0340?+
Clearing it won't help — the fault returns as soon as the sensor signal drops again, and the car may leave you stranded until it's repaired.
Related codes
Often seen with P0340
Read & clear P0340 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX