What does it mean?
P1377 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Camshaft Position Sensor Master Camshaft Not Defined .
Symptoms
- MIL on, often together with cam and crank correlation codes
- Long cranking before the engine fires
- Rough idle and hesitation off idle
- Reduced power because the module falls back to a default ignition and fuel strategy
- Stalling at idle in some cases
Likely causes
- Control module not configured or calibrated correctly for the engine, often after a module replacement
- Missing or intermittent signal from the camshaft sensor designated as the master
- Cam and crank signals out of correlation because of a stretched or jumped timing chain
- Damaged cam target wheel or a loose camshaft sprocket
- Wiring fault or connector corrosion in the camshaft sensor circuit
- Variable valve timing actuator stuck away from its base position
- Failed camshaft position sensor
How to fix it
- Read all stored codes, cam, crank and valve timing codes usually point to the root cause
- Confirm the control module carries the correct calibration and configuration for that engine
- Watch the cam and crank signals in live data or on a scope at idle
- Inspect the cam sensor connectors and harness for oil contamination and chafing
- Verify the mechanical timing against the marks before doing further electrical work on a suspect chain
- Test the valve timing solenoid operation and check its oil feed screen for sludge
- Replace the sensor or repair the timing components, then run the cam position relearn procedure