P0021 OBD-II: "A" Camshaft Position - Timing Over-Advanced or System

What Does P0021 Code Mean?

OBD-II Code P0021 is defined as a "A" Camshaft Position - Timing Over-Advanced or System

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.

P0021 Symptoms

• 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

• Oil and Filter Change