P0021 - OBD II Trouble Code

Our automotive experts have put together the following information about the P0021 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0021 code.

OBD II Fault Code

  • OBD II P0021

    Fault Code Definition

    • "A" Camshaft Position - Timing Over-Advanced or System

    What does this mean? The engine control module (PCM) uses a signal from the camshaft position sensor to determine the the proper time to fire the fuel injectors and ignite the spark plugs. The PCM compares this signal to the signal from the crankshaft to determine if the engine is timed properly. Newer vehicles use a variable timing system to adjust when the intake and exhaust valves open and close to increase fuel efficiency and performance. If the Camshaft is not in the proper position relative to the crankshaft, the PCM will set code P0021.


    • Decreased engine performance
    • Increased fuel consumption

    Common Problems That Trigger the P0021 Code

    • Camshaft variable timing solenoid failure
    • Engine oil level is too low
    • The engine is not timing correctly
    • The engine oil does not meet the manufacturer's requirements
    • Variable valve timing actuator failure
    • Worn timing chain

    Common Repairs Needed for the P0021 Code

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