Dirty or low engine oil
Oil control valve
Variable Valve Timing controller assembly
Engine Control Module (ECM)
Engine Light ON (or Service Engine Soon Warning Light)
Variable Valve Timing (VVT) system controls the intake valve timing to proper timing in response to driving condition. The Engine Control Module (ECM) controls Oil Control Valve (OCV) to make the intake valve timing properly, and, oil pressure controlled with OCV is supplied to the VVT controller, and then, VVT controller changes relative position between the camshaft and the crankshaft.