What does it mean?
P1337 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Camshaft Position Sensor (Bank 1) Short to Ground .
Symptoms
- Extended cranking or a no-start, because the module cannot establish cylinder identification
- Engine stalls and may restart in a limited backup mode
- Rough running and misfire on start-up until synchronisation is recovered
- Check engine light on, often with crank/cam correlation or misfire codes stored alongside
- Reduced power and disabled variable valve timing on many engines
Likely causes
- Signal wire chafed against the cylinder head, a bracket or a metal clip and shorted to ground
- Oil or coolant intrusion into the sensor connector, bridging the signal pin to the shield or ground pin
- Internally shorted camshaft position sensor
- Harness pinched or trapped during previous work on the timing cover or valve cover
- Melted insulation where the harness passes close to the exhaust manifold or turbocharger
- Corroded or bent terminals inside the connector making unintended contact
- Damaged module driver or input pin, which is the last item to consider
How to fix it
- Check the freeze frame and note whether the fault sets while cranking, at idle or only when the engine is hot
- Unplug the CMP sensor on bank 1 and inspect the connector for oil, since a leaking cam seal wicking into the plug is a common cause
- With the sensor unplugged, measure resistance from the signal wire to ground; a very low reading confirms the short
- Follow the harness along the head, looking for chafe points, missing clips and melted sections near hot components
- Verify the sensor supply voltage and ground are correct before condemning the sensor
- Watch the cam signal in live data while cranking to see whether pulses appear once the wiring is repaired
- Replace the sensor if it is internally shorted, then clear the code and confirm cam and crank signals both appear during cranking