XC70 L5-2.5L Turbo VIN 59 B5254T2 (2003)
Canister Purge Control Valve: Description and Operation
Evaporative Emission System (EVAP) Valve
The evaporative emission system (EVAP) valve is used to open/close the connection between the EVAP canister and the intake manifold. The valve
controls the flow of hydro-carbons (fuel vapor) from the EVAP canister to the engine intake manifold using the vacuum in the intake manifold. This
ensures that hydro-carbons stored in the EVAP canister are used in the engine combustion process.
The valve is an electro-magnetic valve which is powered from the system relay. When the valve needs to be opened, it is grounded internally in the
engine control module (ECM). The evaporative emission system (EVAP) valve is closed when in the standby position (open-circuit).
When the control module requests that the EVAP canister should be emptied (the hydrocarbons stored in the canister should be released into the engine),
the control module deploys the evaporative emission system (EVAP) valve by grounding it. The valve is grounded using a pulse width modulation
(PWM) signal, allowing the control module to govern the extent to which the valve opens and adapting the emptying of the canister according to how
full it is, engine speed (rpm) and load etc.
The engine control module (ECM) can diagnose the evaporative emission system (EVAP) valve. The valve can be activated using VADIS/VIDA.
The evaporative emission system (EVAP) valve is close to the intake manifold.
