P0390
UniversalCamshaft Position Sensor B Circuit (Bank 2)
The engine computer monitors the electrical signal from camshaft position sensor B on bank 2 to track camshaft position and coordinate engine operation. This code means it detected a problem in that sensor circuit; it does not by itself prove the sensor has failed. Depending on the vehicle and the fault, engine performance or starting may be affected, or there may be no noticeable symptoms.
⚠️ Before You Begin (Safety First)
If the engine stalls, runs very poorly, or is difficult to keep running, stop in a safe place and arrange professional help rather than continuing to drive. If the warning light is on but the vehicle runs normally, arrange diagnosis soon and watch for changes in how it runs.
Common Symptoms
- The check-engine light may be on, with no obvious change in how the vehicle runs.
- Starting may take longer or the engine may be difficult to start if the signal is unreliable.
- The engine may run roughly, hesitate, or lose power if engine control is affected by the missing or inconsistent camshaft signal.
- The engine may stall in some cases if the control system cannot maintain reliable operation.
Common Causes
- A faulty camshaft position sensor B on bank 2 may produce an absent or unreliable signal.
- A loose, damaged, corroded, or contaminated sensor connector can interrupt the circuit.
- Damaged wiring or a poor electrical connection can disrupt the sensor signal.
- A problem elsewhere in the circuit or engine control system may prevent the signal from being read correctly.
- A camshaft signal or mechanical timing issue may need to be considered if circuit checks do not explain the code.
Diagnostic Steps
- Note whether the engine has starting, running, or stalling problems, and avoid driving if it cannot run reliably.
- With the engine off and cool, look for visible damage, looseness, or corrosion at accessible wiring and connectors associated with camshaft position sensor B on bank 2. Do not pull on wires or disconnect components while the engine is running.
- Check the vehicle's owner information for the correct method to identify bank 2 and sensor B; their physical locations vary by engine.
- If you have a suitable scan tool, record the code and any related codes before clearing anything. This information can help guide diagnosis.
- If the code returns or symptoms are present, have the circuit and sensor signal tested using vehicle-specific service information rather than replacing a part based only on the code.
When to Call a Professional
Confirm the code and check for related codes and available scan data before replacing parts. Inspect the sensor connector and wiring, then test the circuit and sensor signal using service information for the exact model, year, and engine. Where appropriate, compare camshaft and crankshaft signals to help distinguish a circuit fault from a signal or timing issue.
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Commonly Asked Questions
Does P0390 prove that camshaft position sensor B needs replacement?
No. The code identifies a detected problem in the sensor B circuit on bank 2. The sensor, connector, wiring, or another signal-related issue may be responsible, so testing is needed before replacing parts.
Can I drive with P0390?
It depends on how the vehicle runs. If it starts and runs normally, arrange diagnosis soon and monitor it. If it stalls, runs very poorly, or is hard to keep running, stop safely and seek assistance.
What does bank 2 and sensor B mean?
Bank 2 identifies one side of the engine, while sensor B distinguishes a camshaft sensor circuit from another camshaft sensor circuit. Their exact locations and naming depend on the engine, so check vehicle-specific information.
Why might there be no noticeable symptoms?
The engine computer may still be able to operate despite an intermittent or limited signal problem. The warning light can appear before a clear drivability change, so the circuit should still be checked.
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