P003C: A Camshaft Profile Actuator A Control Performance/Stuck Off Bank 1

What does P003C mean?

The camshaft profile actuator A switches the intake camshaft (camshaft A) on bank 1 between fixed cam profiles, usually a low-lift base profile and a high-lift profile. In most designs the unactuated state ("off") is the base profile; which profile counts as "on" is defined by the manufacturer. The control module does not need a position sensor to check the switchover: it detects the actual profile indirectly, for example from oil pressure in the switching gallery, intake pressure per cylinder or crankshaft speed fluctuations. This code is set when the switchover is commanded but the camshaft stays on the base profile, or switches too slowly or incompletely. The engine then lacks power at higher engine speed.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Lack of power at higher engine speed
• Reduced power mode on some vehicles

Common causes

• High Oil level too low, wrong viscosity or sludged oil, so switching pressure is missing
• High Profile switching solenoid sticking or its screen clogged
• Medium Oil supply to the switching elements leaking or restricted, e.g. worn seals
• Medium Locking pin in tappet or rocker arm, or sliding cam piece, sticking
• Low Consequence of a circuit fault of the same actuator

Likelihood is a general estimate across vehicles; your make and model may differ.