Engine

P0390 — Camshaft Position Sensor B Circuit Malfunction (Bank 2)

Severity: medium Drive with care, to a shop

What P0390 means

The engine control module uses the camshaft position signal to know the engine's phase and to time fuel injection, ignition and variable valve timing. P0390 sets when the signal from sensor B on Bank 2 is missing, erratic or out of range. The cause may be the sensor itself, its wiring, or a timing drive problem.

Symptoms

  • Check Engine light on
  • Rough idle or misfires
  • Reduced power and sluggish acceleration
  • Hard starting or no-start
  • Possible stalling while driving
  • Poor fuel economy

Possible causes

  1. Failed camshaft position sensor B (Bank 2)
  2. Damaged wiring harness or connector at the sensor
  3. Open or short in the sensor circuit (to ground or power)
  4. Poor connection or corroded terminals
  5. Timing misalignment: stretched chain or jumped belt or chain
  6. Damaged or dirty camshaft reluctor wheel or target
  7. ECM fault (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data; look for related crankshaft or other camshaft sensor codes
  2. Identify which sensor is B on Bank 2 using the diagram for your engine
  3. Inspect the sensor, connector and harness for chafing, oil, heat damage and corrosion
  4. Check supply voltage, signal and ground at the connector with a multimeter
  5. Test wire continuity between the sensor and ECM for opens and shorts
  6. Compare the camshaft signal with the crankshaft signal on a scope
  7. Verify cam timing, chain or belt condition and tensioners
  8. If wiring and mechanics are good, test the ECM

Common fixes

  • Replace camshaft position sensor B
  • Repair the wiring harness or replace the damaged connector
  • Clean the terminals and fix the source of oil contamination
  • Correct the cam timing, replacing the chain, belt or tensioner as needed
  • Repair or replace the ECM once confirmed faulty

P0390 on different brands

Ford · manuals
On Ford gasoline engines from 2024-2025, P0390:01 refers to the exhaust cam position circuit on Bank 2; it identifies the monitor condition detected rather than a confirmed failed part.

Questions and answers

Can I drive with a P0390 code?

Only for a short distance, such as to a repair shop. The engine may lose power, misfire or stall, so avoid long trips or highway driving.

What most often causes P0390?

Most often it's a failed camshaft sensor or damaged wiring or connector. Mechanical timing issues are less common but should be ruled out if the electrical side checks out.

Is replacing the sensor enough?

Not always. Check the harness, connector and sensor power first, otherwise the new sensor may set the same code again.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.