Monitor Description

The ECM optimizes the intake valve timing using the VVT (Variable Valve Timing) system to control the intake camshaft. The VVT system includes the ECM, the Oil Control Valve (OCV) and the VVT controller. The ECM sends a target duty-cycle control signal to the OCV. This control signal regulates the oil pressure supplied to the VVT controller. The VVT controller can advance or retard the intake camshaft. If the difference between the target and actual intake valve timings is large, and changes in actual intake valve timing are small, the ECM interprets this as the VVT controller stuck malfunction and sets a DTC. Example:

A DTC is set when the following conditions 1), 2) and 3) are met:

1) The difference between the target and actual intake valve timings is more than 5°CA (Crankshaft Angle) and the condition continues for more than 4.5 seconds.

2) It takes 5 seconds or more to change the valve timing by 5°CA.

3) After above conditions 1) and 2) are met, the OCV is forcibly activated 63 times or more. DTCs P0011 and P0021 (Advanced Cam Timing) are subject to 1 trip detection logic.

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