Fault code P0012 – a step-by-step guide to diagnosing and fixing it

Error code P0012 is displayed and the check engine light is on - what does this mean?

With this DTC (Diagnostic Trouble Code), the OBD/EOBD system detects a malfunction in the camshaft phasing on the intake side. Error code P0012 indicates that the camshaft of bank 1 is retarded or retarded too far. This OBD code can occur with different manufacturers, whereby the specific tolerance values can vary slightly.

What causes can this error code have?

• Defective camshaft phaser
• Contaminated or incorrect engine oil
• Clogged oil strainer or defective oil filter
• Defective solenoid valve for the camshaft phasing unit
• Damaged or dirty camshaft sensors
• Defective timing chain or timing belt
• Blocked oil ducts in the camshaft phasing unit
• Low oil pressures in the engine system
• Faulty wiring or plug connections
• Faulty engine control unit (ECM/PCM)

What symptoms occur in parallel with fault code P0012?

• Starting problems: The vehicle is difficult to start or starts irregularly
• Loss of power: Significantly reduced engine power, especially at low engine speeds
• Unsteady idling: Engine runs unevenly or stutters at idle speed
• Increased fuel consumption: Noticeably higher consumption due to inefficient combustion
• Knocking noises: Metallic noises from the engine compartment, especially when starting cold
• Exhaust problems: Increased emission values or visible smoke development
• Jerking when accelerating: Uneven power delivery under load

How can the problem with error code P0012 be rectified?

• The repair requires a systematic diagnosis to identify the exact cause.
• Change the engine oil and filter: Use the oil viscosity specified by the manufacturer and replace the oil filter, as contaminated oil is the most common cause of this fault code
• Replace camshaft phasing unit: Replace the defective adjuster completely if there is mechanical damage or cleaning was unsuccessful
• Check and replace the camshaft phasing solenoid valve: Test the electrical values of the valve and replace it if there are any deviations
• Check oil pressure system: Measure the oil pressure and repair defective oil pumps or clogged lines in the system
• Check timing chain or timing belt: Check the tension and condition, replace worn components including tensioners and guides
• Replace camshaft sensors: Replace defective sensors and clean any dirt from the connection points
• Repair wiring and plug connections: Check all electrical connections for corrosion, breaks or loose contacts and repair them