Toyota 2GR-FE Manual page 567

The following two monitors run to confirm the appropriate EVAP system operation.
1. Key-off monitor
This monitor checks for EVAP (Evaporative Emission) system leaks and canister pump module
malfunctions. The monitor starts 5 hours* after the ignition switch is turned off. At least 5 hours are
required for the fuel to cool down to stabilize the EVAP pressure, thus making the EVAP system
monitor more accurate.
The leak detection pump creates negative pressure (vacuum) in the EVAP system and the pressure
is measured. Finally, the ECM monitors for leaks from the EVAP system, and malfunctions in both the
canister pump module and purge VSV, based on the EVAP pressure.
HINT:
*: 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.
2. Purge flow monitor
The purge flow monitor consists of the two monitors. The 1st monitor is conducted every time and the
2nd monitor is activated if necessary.
• The 1st monitor
While the engine is running and the purge VSV (Vacuum Switching Valve) is ON (open), the ECM
monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not
created, the ECM begins the 2nd monitor.
• The 2nd monitor
The vent valve is turned OFF (open) and the EVAP pressure is measured. If the variation in the
pressure is less than 0.5 kPa-g (3.75 mmHg-g), the ECM interprets this as the purge VSV being
stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic).
Atmospheric pressure check:
In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before
and after conduction of the purge flow monitor, is measured by the ECM.
EVAP Purge Flow:
Purge VSV
(ON)
To Intake Manifold
ECM
Soak Timer
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
Reference Orifice (0.02 inch)
Fuel Cap
Canister Pressure Sensor
Fuel Tank
Air Filter
Leak Detection Pump (OFF)
ES–411
Refueling Valve
To Atmosphere
Canister
Vent Valve (OFF)
Canister Pump Module
ES
A122571E06