In operation D, the canister pressure sensor measures the EVAP (Evaporative Emission) system pressure. The pressure measurement for
purge VSV monitor begins when the purge VSV is turned on (open) after the EVAP leak check. When the measured pressure indicates an
increase of 0.3 kPa (2.25 mmHg) or more, the purge VSV is functioning normally. If the pressure does not increase, the ECM interprets
this as the purge VSV being stuck closed. The ECM illuminates the MIL and sets the DTC (2 trip detection logic).
2. PURGE FLOW MONITOR
The purge flow monitor consists of the 2 step 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 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 on (closed) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.15 kPa (1.13
mmHg), 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.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
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