Camshaft Reset Valve (CVVT)

Courtesy of VOLVO CARS CORPORATION

The camshaft reset valve controls the oil flow to the CVVT unit (camshaft pulley).

The valve consists of an electro-magnetic valve with a spring-loaded piston. There are slits in the piston which channel the engine lubricating oil to the CVVT unit by moving the piston in the reset valve. The continuous variable valve timing (CVVT) unit turns the camshaft (the camshaft timing changes). The direction in which the camshaft turns depends on the chamber in the CVVT unit which is supplied with oil (pressure). See also: FUNCTION  

An oil filter is mounted at the intake channel for the valves to prevent oil contaminants from affecting the function of the reset valves.

The system relay supplies the reset valve with voltage via a fuse. The valve is grounded (control stage) internally in the engine control module (ECM). When the valve is grounded using a pulse width modulation (PWM) signal, the oil flow in the valve can be regulated to the different chambers in the continuous variable valve timing (CVVT) unit at variable rates. This allows the angle position to be changed precisely and steplessly.

The engine control module (ECM) can diagnose the camshaft reset valve.

The valve is located on the cylinder head above the camshaft. There is a valve for intake camshaft.

There is no valve for the exhaust camshaft.