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OBD II Code: P0020

Copyright AA1Car

Definition: A Camshaft "A" Actuator Fault (Bank 2)

This means the OBD II system has detected a problem in the Variable Valve Timing system that controls camshaft and valve timing. This code is set when the camshaft is not changing timing because of an electrical fault in the Variable Valve Timing control circuit.

The "A" cam usually refers to the intake camshaft on Dual Overhead Cam (DOHC) engines, or the intake camshaft for the cylinder head opposite the number one cylinder (bank 2) on a V6 or V8 engine.

Intake and exhaust camshaft timing is typically retarded at higher RPM to increase power, and advanced at mid-range RPM under light load to reduce pumping losses and improve fuel economy. Exhaust cam timing may be retarded when the engine is under load to reduce oxides of nitrogen (Nox) emissions.

The timing position of the camshaft is controlled by a cam phaser that is part of the camshaft drive gear or sprocket. The phaser rotates the cam�s relative position clockwise or counterclockwise to change timing using oil pressure and either a helical gear or lobed or vaned rotor inside the phaser housing.

variable valve timing cam phasers .

Possible Symptoms:

Maybe None

Reduced power at higher engine speeds

Reduced fuel economy

Possible Causes:

Defective VVT oil flow control valve solenoid

VVT oil flow control valve solenoid shorted or open

Fault in VVT oil flow control valve wiring connector or wiring harness


Check wiring connections at oil flow control valve solenoid to make sure the connector is clean, tight and free from corrosion.

Check wiring continuity at oil flow control valve solenoid.

Check solenoid resistance with ohmmeter. Replace if resistance is out of specifications.

Remove oil flow control valve (engine OFF) and test the solenoid by applying voltage. If solenoid valve does not move, the unit is defective and needs to be replaced

Check wiring between oil flow control valve solenoid and PCM for shorts or opens.

Use scantool to check status of VVT oil flow control valve. Typically, it should be OFF at idle and ON at higher engine RPM.

If oil flow control valve is pulse width modulated, duty cycle should change with RPM. No change would indicate a problem with the engine computer.

If PCM commands to VVT oil flow control valve are correct, but cam phaser is not changing cam timing correctly or returning cam timing back to base timing after advance command, the oil control valve solenoid is defective, or there is a wiring fault at the solenoid connector or in the wiring between the PCM and solenoid.

VVT oil flow control valve
The location of the oil flow control valve will vary depending on the application,
but is typically on the front timing cover or valve cover.


Replace VVT oil flow control valve solenoid, or repair wiring as needed.

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