What does it mean?
P1397 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Camshaft Position Sensor Circ Malfunction .
Symptoms
- MIL on, long cranking before the engine fires
- Intermittent stalling and occasional no-start
- Rough running, hesitation and a lack of power
- Engine runs in a default strategy with degraded response
- Higher fuel consumption and, on some vehicles, no tachometer reading
Likely causes
- Faulty camshaft position sensor or a worn hall element
- Corroded, loose or oil-filled sensor connector
- Broken, chafed or shorted wiring between the sensor and the control module
- Missing supply voltage or an open sensor ground
- Damaged cam trigger wheel, a sheared sprocket key or a loose sensor mounting
- Incorrect valve timing after chain or belt service
- Strong electrical interference from arcing secondary ignition components
How to fix it
- Check whether the code appears together with crank sensor or timing codes, which changes the approach
- Inspect the connector and harness closely, oil intrusion is the most common finding
- Measure the sensor supply and ground, then check the signal while cranking
- Scope the sensor output and confirm a clean square or pulse pattern with no dropouts
- Check the mounting, the air gap and the condition of the trigger wheel
- Confirm valve timing against the marks if the sensor signal is present but mistimed
- Replace the sensor when the circuits test good, then clear the code and verify with a cold start