Possible causes

– Incorrect camshaft timing
– Faulty Valve Control Timing (VCT) position solenoid
– Valve Control Timing (VCT) position circuit is open or shorted
– Valve Control Timing (VCT) position circuit poor electrical connection

Symptoms

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

P0021 FORD Description

The Engine Control Module (ECM) has detected the Valve Control Timing (VCT) position in an over advance condition- Camshaft timing over advanced