Variable valve timing (VVT) changes camshaft timing while the engine is running to improve power, fuel economy and emissions. Most systems use engine oil pressure, controlled by a solenoid, to rotate a cam phaser on the end of the camshaft.
Main Components
- VVT solenoid (oil control valve): commanded by the engine computer to direct oil to the phaser.
- Cam phaser (VVT gear): a hydraulically operated sprocket that advances or retards the camshaft relative to the chain or belt.
- Camshaft and crankshaft position sensors: let the computer compare actual timing to the commanded value.
Common Symptoms
- Check engine light with camshaft timing codes, such as the generic P0010 to P0025 range.
- Rough idle, hesitation or reduced power.
- A knocking or rattling noise from a phaser on startup.
Check the Basics First
Because the system depends on oil pressure, many VVT faults start with the oil. Before replacing parts, check:
- Oil level, condition and the correct viscosity for the engine.
- Screens or filters in the oil passage to the solenoid, which can clog with sludge.
- Wiring and connector condition at the solenoid and sensors.
- Timing chain stretch, which can set similar timing codes.
Replacing VVT Components
If a solenoid or phaser is confirmed faulty, replace it with the part that matches the engine and bank. On engines where the chain, guides and tensioner are also worn, replacing the phaser together with a timing chain kit avoids a second teardown. Follow the service procedure for camshaft locking and timing alignment.
Evergreen VVT and Timing Parts
Browse Evergreen variable valve timing and sensor parts and timing chain components, or search by engine in the Evergreen eCatalog.
