P0394
Camshaft Position Sensor B Circuit Intermittent Bank 2.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 3
- AreaIgnition system or misfire
- 94
- FaultThe specific fault in that area
What it means
P0394 is the generic code for an intermittent fault in the camshaft position sensor B circuit on bank 2. The engine control unit saw the sensor signal drop out, become erratic or disagree briefly with the crankshaft position signal, rather than failing completely. Which camshaft is 'B' (usually the exhaust cam) and which bank is bank 2 depends on the engine, so confirm this for the vehicle in question.
Symptoms
- Engine warning light on
- Intermittent hesitation or misfire
- Occasional long cranking or delayed starting
- Random stalling, especially when warm
- Loss of power or the car entering limp mode
- Rough idle that comes and goes
Possible causes
- Damaged, chafed or corroded wiring to the bank 2 camshaft sensor Blikely
- Loose, dirty or corroded connector at the sensor or control unitlikely
- Failing camshaft position sensor with heat-related or intermittent dropoutlikely
- Oil contamination or metal debris on the sensor tip or reluctor/trigger wheelpossible
- Incorrect sensor air gap, loose mounting or damaged trigger wheelpossible
- Camshaft timing out of position due to a stretched chain or worn tensioner or phaserpossible
- Fault within the engine control unitrare
How to diagnose
- Read all stored and pending codes and note any related cam, crank or misfire codes
- Review freeze frame data for engine speed, load and temperature when the fault set
- Locate the bank 2 camshaft sensor B for this engine and inspect its wiring for chafing, heat damage and oil soaking
- Check the connector for security, bent or pushed-back pins, moisture and corrosion
- With the engine running, wiggle the harness and connector while watching live cam and crank data for dropouts
- Remove the sensor and inspect the tip and mounting for debris, damage or oil contamination
- Check the sensor supply voltage, earth and signal wiring against the manufacturer's data for continuity and shorts
- Compare cam and crank correlation and timing against specification, and inspect the trigger wheel and timing components if indicated
How to fix
- Repair or replace damaged wiring and fix any chafing points
- Clean, repair or replace the corroded or loose connector terminals
- Replace the camshaft position sensor B on bank 2 if it fails testing
- Clean debris from the sensor area and fix any oil leak that is contaminating it
- Correct the sensor mounting or replace a damaged trigger wheel
- Repair worn timing components so cam timing returns to specification
Can I keep driving?
Medium severity
Short trips are usually possible, but the engine may stall or lose power without warning, which is a safety risk in traffic. Get it checked soon and avoid long journeys until it is fixed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.