P0340: The camshaft position sensor on Bank 1 has a circuit fault
Camshaft Position Sensor A Circuit Malfunction (Bank 1 or Single Sensor)
There is a fault in the camshaft position sensor circuit, so fuel and spark timing may be off. Get it checked today. If it stalls, misfires or will not start, have it towed.
Stop driving and get help if
- The check engine light is flashing
- The temperature gauge runs high, or you see steam (overheating)
- The car loses power, hesitates badly or stalls
- You smell burning or see smoke
- A brake warning light comes on, or the brakes feel different
Pull over as soon as you can, turn the engine off, and call a tow or roadside help.
What it means
The camshaft position sensor tells the PCM where the camshaft is positioned relative to the crankshaft. The PCM needs this to determine which cylinder is on its compression stroke so it can fire the correct injector and coil. P0340 means the PCM received no usable signal from the sensor circuit, as opposed to P0341 which is a range or performance fault. Without cam position data, the PCM falls back to crank sensor data alone, which means it may need extra cranking to synchronize and fueling will not be as precise. On engines with variable valve timing, this code can also disable the VVT system entirely.
Common causes
- Failed camshaft position sensorThe Hall-effect sensor element fails. Common on engines with 100,000 or more miles.
- Open or short in the cam sensor wiring harnessThe harness near the cam cover is exposed to oil and heat. Damaged insulation causes the circuit to fail.
- Damaged camshaft reluctor ring or tone wheelDebris from timing chain wear can chip the reluctor ring, breaking the signal pattern.
- Timing chain stretch or jumped timingA stretched chain shifts cam position relative to crank. The sensor signal is present but out of phase, which can also set this code.
- Failed PCM input circuit for the cam sensorUncommon. Confirm the sensor and wiring are good before suspecting the PCM.
What the fix could involve
From the cheaper fix to the bigger one. Prices depend on your car, your area and the shop, so ask for a written quote that names the part and the labor before you approve it.
- Camshaft position sensor replacement
- Wiring or connector repair
- Timing chain and guides replacement (if stretched)
Symptoms
- Check engine light on, often steady
- Hard starting or extended crank time
- Rough idle and reduced performance
- Variable valve timing disabled (on VVT engines)
- Possible stalling under load
What to do next
Inspect the wiring and connector at the sensor first. A broken wire near a hot valve cover is a common and cheap fix. If wiring is fine, replace the sensor. If the code returns immediately, or if you also have symptoms like a rattle on start-up, have a shop check the timing chain. A skipped or stretched chain requires prompt repair because continued operation can damage valves and pistons.
Lewis reads P0340 alongside any related cam and crank codes, so you can see whether it is a sensor fault on its own or paired with a timing correlation code. Get Lewis on the App Store or Google Play.
Related codes
FAQ
- Can P0340 cause the car to not start at all?
- Yes. Some PCMs will not fire injectors without a valid cam signal. Others use crank sensor data as a fallback. Whether it starts depends on the specific vehicle and PCM logic.
- How do I know if the timing chain is the real cause?
- If you hear a rattle on cold starts, especially one that clears as oil pressure builds, that is a timing chain warning. A stretched chain will also set P0017 or similar cam-crank correlation codes.
- Bank 1 Sensor A -- is there a Bank 2 version?
- Yes, P0345 is the Bank 2 cam sensor circuit code. On V-engines with variable valve timing on both banks, each bank has its own sensor.
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