Monitor Description

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

Example:
A DTC is stored when the following conditions 1 and 2 are met:
- 1. It takes 5 seconds or more to change the valve timing by 5°CA.
- 2. After condition 1 is met, the camshaft timing oil control valve is forcibly activated for 10 seconds.
These DTCs indicate that the VVT controller cannot operate properly due to camshaft timing oil control valve malfunctions or the presence of foreign objects in the camshaft timing oil control valve.