Camshaft Position Sensor B Circuit Range/Performance (Bank 2)

What does P0391 mean?

P0391 stands for Camshaft Position Sensor B Circuit Range/Performance (Bank 2). The engine computer has detected an ignition problem or a misfire, meaning one or more cylinders are not burning fuel properly.

Powertrain codes cover the engine, transmission and emissions. When the car's computer sees a reading outside its normal range, it stores this code and may turn on a warning light on the dashboard.

Common causes

• Worn spark plugs
• Faulty ignition coil or plug wires
• Clogged fuel injector
• Vacuum leak
• Low compression

What to do

1. Read all stored and pending codes with a scanner. Several codes together often point to one cause.
2. Note the freeze frame data (speed, temperature, load) recorded when the code was set.
3. Inspect the wiring and connectors of the part named in the code for damage, corrosion or looseness.
4. Fix the most likely and cheapest cause first, then clear the code and drive to see if it comes back.

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Frequently asked questions

What does P0391 mean?

P0391 means “Camshaft Position Sensor B Circuit Range/Performance (Bank 2)”. It belongs to the ignition system or misfire group: The engine computer has detected an ignition problem or a misfire, meaning one or more cylinders are not burning fuel properly.

Is it safe to drive with P0391?

Avoid driving long distances. This kind of fault can cause damage or affect safety, so get it checked as soon as possible.

How do I clear P0391?

Fix the cause, then clear the code with an OBD2 scanner or app. If the fault is still there, the code will come back.

Related codes

• P0387Crankshaft Position Sensor B Circuit Low Input
• P0388Crankshaft Position Sensor B Circuit High Input
• P0389Crankshaft Position Sensor B Circuit Intermittent
• P0390Camshaft Position Sensor B Circuit (Bank 2)
• P0392Camshaft Position Sensor B Circuit Low (Bank 2)
• P0393Camshaft Position Sensor B Circuit High (Bank 2)
• P0394Camshaft Position Sensor B Circuit Intermittent (Bank 2)
• P0400Exhaust Gas Recirculation Flow Malfunction

Code meanings can vary by manufacturer. This page is general guidance, not a repair manual. Always confirm the cause before replacing parts.