Camshaft Position Sensor "B" Circuit (Bank 2)
P0390 indicates the PCM detected a malfunction in the Camshaft Position Sensor B circuit on Bank 2. This sensor helps the engine control module determine precise camshaft timing for fuel injection and ignition, so a failure disrupts engine operation and may prevent proper starting.
What You Might Notice
- Hard starting or inability to start the engine
- Rough idle or misfiring during acceleration
- Loss of engine power or reduced performance
- Check Engine Light illuminated
- Possible stalling while driving
Most Common Causes
- 1
Faulty Camshaft Position Sensor B
The sensor itself has failed electrically or mechanically. Bank 2 sensors are common failure points due to heat and vibration exposure near the engine.
- 2
Wiring or Connector Issues
Corroded, broken, or shorted wires/connectors in the camshaft position sensor circuit disrupt signal transmission to the PCM. Moisture intrusion is a frequent culprit.
- 3
PCM Malfunction
The Powertrain Control Module itself may have failed or lost calibration, preventing proper interpretation of the camshaft sensor signal.
- 4
Crankshaft Position Sensor Failure
Related sensor malfunction can cause the PCM to fail synchronizing crankshaft and camshaft signals, triggering this code.
How to Diagnose It
- 1
Check Faulty Camshaft Position Sensor B — The sensor itself has failed electrically or mechanically. Bank 2 sensors are common failure points due to heat and vibration exposure near the engine.
- 2
Check Wiring or Connector Issues — Corroded, broken, or shorted wires/connectors in the camshaft position sensor circuit disrupt signal transmission to the PCM. Moisture intrusion is a frequent culprit.
- 3
Check PCM Malfunction — The Powertrain Control Module itself may have failed or lost calibration, preventing proper interpretation of the camshaft sensor signal.
- 4
Check Crankshaft Position Sensor Failure — Related sensor malfunction can cause the PCM to fail synchronizing crankshaft and camshaft signals, triggering this code.
How to Fix It
- 1
Test and replace camshaft position sensor B
Use a multimeter to verify sensor output voltage and resistance per manufacturer specs. If out of range, replace the sensor. Bank 2 is the side opposite cylinder #1.
- 2
Inspect and repair wiring circuit
Visually inspect the sensor harness from connector to PCM for corrosion, cracks, or loose pins. Repair or replace damaged sections and apply dielectric grease to connectors.
- 3
Test crankshaft position sensor
Verify the crankshaft position sensor on Bank 2 is functioning properly, as camshaft sensor codes often relate to crankshaft/camshaft synchronization failure.
- 4
PCM diagnosis and reprogramming
If sensors and wiring test good, the PCM may require reprogramming or replacement. Have a professional scanner perform a full diagnostic to rule out internal PCM faults.
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