P0340: Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)
The engine computer is not getting a good signal from the camshaft position sensor on bank 1.
What P0340 means
The camshaft position sensor tells the engine computer which stroke each cylinder is on. Combined with the crank sensor, that lets it time sequential fuel injection and coil-on-plug spark correctly. RepairPal explains that when the cam signal is interrupted for any reason, P0340 sets. Some engines will still start and run on crank signal alone, but many crank longer, stumble or stall. KBB calls it unsafe to drive because you can lose power on the road. A failed sensor is common, and so is a wiring or connector problem, including oil that wicks into the connector past a leaking sensor seal. RepairPal also lists a bad crank sensor as a cause that gets confused with this one. Less often, a stretched or jumped timing chain or belt puts the cam signal out of place. Shops check the cam signal on a scope or scan tool, test power and ground, and compare cam and crank timing before replacing parts.
Common symptoms
- Check engine light on
- Hard starting or long cranking
- Engine stalling
- Hesitation or misfire
- Car may not restart after stalling
Most common causes
- Failed camshaft position sensor
- Damaged or corroded sensor wiring or connector
- Faulty crankshaft position sensor
- Timing belt or chain stretched or jumped
- Damaged cam reluctor or tone wheel
What to check yourself first
Check the cam sensor connector, usually on the cylinder head or timing cover, for oil inside it or a loose latch. Oil in the connector can mean a leaking sensor O-ring. Check your oil level too, since low oil can affect cam timing on many engines.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace camshaft position sensor | $224-$326 | The usual fix once wiring is confirmed good. |
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | RepairPal notes cam sensors are often replaced when the issue was a poor connection or chafed wiring. |
| Replace crankshaft position sensor | $230-$335 | If the crank sensor is the real cause. |
| Replace timing chain | $2,120-$2,764 | Only if a timing check shows a stretched or jumped chain. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0341 Camshaft Position Sensor "A" Circuit Range/Performance (Bank 1 or Single Sensor)
- P0345 Camshaft Position Sensor "A" Circuit (Bank 2)
- P0335 Crankshaft Position Sensor "A" Circuit
- P0016 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)
- P0011 "A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)