P0340
Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)
The camshaft position (CMP) sensor signal is missing or implausible. The ECU uses CMP together with CKP to identify cylinder phase for sequential injection and coil-on-plug ignition; without CMP the engine may run on group injection or fail to start.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
What we see in the workshop
ON FORD ECOBOOST
Camshaft position sensor faults on Ti-VCT engines can be the sensor, the phaser or chain stretch presenting as a sensor fault. We verify cam timing before replacing the sensor.
Symptoms
- Check engine light on
- Power loss especially in mid-rpm range
- Possible rough idle or stalling
- Increased fuel consumption
Common causes
Ordered by how often each turns out to be the cause.
- Sensor failedCommon
- Timing chain stretched, throwing off sensor timingPossible
- Wiring faultLess likely
Parts involved
- Camshaft Position Sensor
- Timing Chain
- Timing Belt
P0340 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.