Evaporative emission system switching valve control

The vent valve is built into the canister pump module.

The description can be found in the evap (evaporative emission) system (see page es-335).

Refer to the evap system (see page es-340).

5 Hours* after the ignition switch is turned off, the leak detection pump creates negative pressure (vacuum) in the evap system. The ecm monitors for leaks and actuator malfunctions based on the evap pressure.

*: If the engine coolant temperature is not below 35°c (95°f) 5 hours after the ignition switch is turned off, the monitor check starts 2 hours later. If it is still not below 35°c (95°f) 7 hours after the ignition switch is turned off, the monitor check starts 2.5 Hours later.

*: If only a small amount of fuel is in the fuel tank, it takes longer for the evap pressure to stabilize.

1. P2419: vent valve stuck closed

In operation b, the leak detection pump creates negative pressure (a vacuum) through the reference orifice. The evap system pressure is then measured by the ecm, using the canister pressure sensor, to determine the reference pressure. If the pressure exceeds -1.057 Kpa-g (-7.93 Mmhg-g) 4 seconds after the leak detection pump is turned on, the ecm interprets this as the vent valve being stuck closed.

The ecm illuminates the mil and sets the dtc (2 trip detection logic).

2. P2420: vent valve stuck open (vent)

In operation c, the vent valve turns on (closes) and the evap system pressure is then measured by the ecm, using the canister pressure sensor, to conduct an evap leak check. If the pressure does not increase when the vent valve is open, the ecm interprets this as the vent valve being stuck open. The ecm illuminates the mil and sets the dtc.

"Saturated" indicates that the evap pressure change is less than 0.286 Kpa-g (2.14 Mmhg-g) in 60 seconds.

Refer to checking monitor status (see page es-17).