P0391

Camshaft Position Sensor B Circuit Range/Performance

High severity

Cam sensor B on bank 2 reads in range but plausibility check fails — slow response, drift, or signal does not match expected cam profile.

Common causes

Sensor drift
One of the most commonly reported causes for this code — check this first.
high
Typical part cost: $70-550
Sensor element aged beyond calibration window
Less common, but worth ruling out after the more likely causes.
low
Typical part cost: $70-550
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First things to check

1Confirm the code with a scan tool and check for additional related codes.
2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

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Related codes

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Frequently asked questions

What does P0391 mean?

P0391 means "Camshaft Position Sensor B Circuit Range/Performance (Bank 2)". It is a generic OBD-II code that points to a fault in the ignition system or misfire.

What are the most common causes of P0391?

sensor drift; sensor element aged beyond calibration window; sensor mounting loose - signal damping — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

This code points to a problem that can cause damage or affect safety. Avoid driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.

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