Possible causes

– Cam timing improperly set
– Continuous oil flow to the VCT piston chamber
– VCT solenoid valve stuck open
– Camshaft advance mechanism binding (VCT unit).

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1388 MAZDA Description

The comprehensive component monitor (CCM) monitors the VCT position for over-retarded camshaft timing. The test fails when the camshaft timing exceeds a maximum calibrated value or remains in a retarded position.