P0390
Camshaft Position Sensor B Circuit Bank 2
Camshaft position sensor
Generic OBD-II
High
What it means
P0390 means the engine computer sees a problem in the circuit for camshaft position sensor B on bank 2. This sensor reports the camshaft's position relative to the crankshaft so spark and injection are timed correctly. A fault can cause hard starting, stalling, or in some cases a no-start until the sensor or its wiring is repaired.
High
Can I keep driving? Driveable in some cases, but a lost cam signal can cause stalling, hard starting, or a no-start. Have it diagnosed before relying on the car.
Common symptoms
What you'll notice
- Check-engine light on
- Hard starting, extended cranking, or no-start
- Stalling or rough idle
- Hesitation and reduced power
Common causes
Most likely first
- Faulty camshaft position sensor B (bank 2)Likely
- Damaged or corroded wiring in the sensor circuitCommon
- Loose or backed-out connector at the sensorCommon
- Damaged reluctor/tone wheel or excessive air gapLess often
- Failed ECM (rare — check the sensor and wiring first)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the code is on the bank 2 'B' cam sensor.
- Inspect the sensor connector and harness for corrosion, chafing, or loose pins.
- Check the sensor tip, mounting, and air gap; look for a damaged tone wheel.
- Test the sensor's signal, power, and ground with a scan tool or scope while cranking.
- Replace the camshaft position sensor if its signal is missing or out of spec, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0390?+
Use caution. The engine may stall or become hard to start, and on some vehicles it won't start at all. Diagnose it before depending on the car.
Can I just clear P0390?+
It will return until the sensor, wiring, or connection is repaired — and may leave you unable to restart.
Related codes
Often seen with P0390
Read & clear P0390 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX