Fault code P0023 – a step-by-step guide to diagnosing and fixing it

Error code P0023 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected a fault in the camshaft phasing system on the exhaust side (bank 2). This DTC P0023 indicates a fault in the variable valve timing system, which can lead to performance problems and increased emissions. With various manufacturers, this trouble code can also be referred to as "Exhaust Camshaft Position Actuator Circuit/Open Bank 2".

What causes can this fault code have?

• Defective camshaft position actuator (VVT actuator)
• Blocked or defective solenoid valve for the camshaft phasing unit
• Contaminated or incorrect engine oil
• Damaged wiring harness to the VVT system
• Loose or corroded plug connections
• Defective camshaft sensor
• Mechanical damage to the camshaft phasing system
• Blocked oil ducts in the cylinder head
• Defective engine control unit (ECU)
• Worn timing chain or timing belt

What symptoms occur in parallel with fault code P0023?

• Loss of power: Noticeably reduced engine power, especially at higher engine speeds
• Uneven idling: Engine runs unevenly when stationary
• Increased fuel consumption: Significantly increased consumption due to inefficient combustion
• Starting problems: Difficulty starting the engine, especially when the engine is cold
• Knocking noises: Metallic noises from the engine compartment
• Exhaust problems: Increased emission values and possible failure of the emissions test
• Jerking: Vehicle jerks while driving or accelerating

How can I fix the problem with fault code P0023?

• Repairing fault code P0023 requires a systematic diagnosis and appropriate measures.
• Change the oil to the correct viscosity: Replace old or incorrect oil, observing the manufacturer's specifications for oil quality and viscosity, as the VVT system relies on clean oil
• Clean or replace the VVT solenoid valve: Remove the solenoid valve, clean it thoroughly or replace it completely if it is defective, as clogged valves are often the cause
• Replace the camshaft phaser (VVT actuator): If the actuator is mechanically defective, replace it completely and mark the installation position correctly
• Check wiring harness and plug connections: Check all electrical connections to the VVT system for damage, corrosion or loose contacts and repair them
• Replace camshaft sensor: If the sensor is defective, replace it and then carry out a basic adjustment of the camshaft position
• Flush the oil ducts in the cylinder head: If the oil ducts are blocked, have a professional engine flush carried out to remove all deposits
• Check the timing chain or timing belt: If the timing elements are worn, replace them and readjust the timing at the same time