Possible causes

– Dirty engine oil
– Low engine oil level
– Faulty Oil Control Valve
– Engine mechanical problems

Symptoms

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

P0021 KIA Description

The CVVT (Continuously Variable Valve Timing) system is installed to the chain sprocket of the intake camshaft. This system controls the intake camshaft to provide the optimal valve timing for every driving condition. The Powertrain Control Module (PCM) controls the Oil Control Valve(OCV), based on the signals output from mass air flow, throttle position and engine coolant temperature. The CVVT controller regulates the intake camshaft angle using oil pressure through the OCV. As result, the relative position between the camshaft and the crankshaft becomes optimal, and the engine torque improves, fuel economy improves, exhaust emissions decrease under overall driving conditions.