What mechanism is employed to prevent fuel varnishing in the doser valve?

The mechanism employed to prevent fuel varnishing in the doser valve is through the use of a coolant jacket. This design allows for better temperature regulation of the doser valve. By maintaining an optimal temperature, the coolant jacket helps to prevent the degradation of fuel, which can lead to the formation of varnish. Varnish is a sticky residue that can build up on engine components and adversely affect performance, including the operation of the doser valve.

The coolant jacket circulates coolant around the doser valve, which absorbs excess heat generated during engine operation. By keeping the temperature in check, it ensures that the fuel remains in a stable state, minimizing the risk of varnish formation. This method is highly effective in prolonging the life of the engine components and maintaining efficient operation.