P0391
PowertrainCrankshaft Camshaft Positionmoderate severityCamshaft Position Sensor B Circuit Range/Performance (Bank 2)
What P0391 Means
The Bank 2 camshaft position sensor B signal is out of the expected range or performance window. Timing correlation may be off, affecting drivability.
Symptoms
- Rough idle
- Reduced power
- Illuminated MIL
Common Causes
- Faulty camshaft position sensor
- Damaged tone/reluctor wheel
- Wiring resistance or corrosion
- Cam timing out of correlation
Diagnostic Steps
- Read freeze frame and correlation data
- Inspect tone wheel for damage
- Check wiring continuity and resistance
- Verify cam timing, replace sensor if needed
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ANCEL AD410 →
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Serious DIY~$100
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Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
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Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
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