Possible causes

– Failed Camshaft Actuator
– Variable Camshaft Timing Actuator harness is open or shorted
– Variable Camshaft Timing Actuator circuit poor electrical connection
– Engine mechanical problems

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Lack/Loss of power
– Engine rough idle

P0020 BMW Description

Variable Camshaft Timing ‘A’ (VANOS) Circuit Continuity