SES code P0020

[Doprat]

MY SES light came on the other day on my 2002 BMW 540i. Pulled OBDII code P0020 "Camshaft Position Actuator Circuit (Bank 2)". The only BMW specific definition for P0020 OBDII code I could find was "Variable Camshaft Timing 'A' (VANOS) Circuit Continuity". Could this could be caused by a faulty vanos solenoid or is it something even more serious?

[rf900rkw]

It's a circuit code. Solenoid, wiring, or computer. Got a DVM?

[Doprat]

Thanks for the feedback, is there a way to test the solenoid with a dvm?

[rf900rkw]

Yep, sure can. It's a simple circuit; a pwm controlled two wire solenoid. Typically the resistance across the solenoid winding would be somewhere around 3-7 ohms. Open resistance between the case and windings. key on 12V to the red/white wire. The computer controls ground side on the green wire. Right after start, in the first few seconds, the computer does a selfcheck of the vanos system, activating the solenoid. You should see the voltage on the green wire dip, and then rise back up.