Monitor Description
5 hours* after the engine 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
HINT
*If the engine coolant temperature is not below 35°C (95°F) 5 hours after the engine 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 engine switch is turned off, the monitor check starts 2 5 hours later
| Sequence | Operation | Description | Duration | ||
|---|---|---|---|---|---|
| - | ECM activation | Activated by soak timer 5, 7 or 9 5 hours after engine switch turned off | - | ||
| A | Atmospheric pressure measurement | Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to register atmospheric pressure If pressure in EVAP system not between 70 kPa-a and 110 kPa-a (525 mmHg-a and 825 mmHg-a), ECM cancels EVAP system monitor |
10 seconds | ||
| B | First reference pressure measurement | In order to determine reference pressure, leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if leak detection pump and vent valve operate normally | 60 seconds | ||
| C | EVAP system pressure measurement | Vent valve turned ON (closed) to shut EVAP system Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then measured Write down measured value as it will be used in leak check If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor |
15 minutes(1) | ||
| D | Purge VSV monitor | Purge VSV opened and then EVAP system pressure measured by ECM Large increase indicates normality | 10 seconds | ||
| E | Second reference pressure measurement | After second reference pressure measurement, leak check performed by comparing first and second reference pressure If stabilized system pressure higher than second reference pressure, ECM determines that EVAP system leaking |
60 seconds | ||
| - | Final check | Atmospheric pressure measured and then monitoring result recorded by ECM | - | ||
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- P0455 EVAP gross leak
In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured If the stabilized system pressure is higher than [second reference pressure x 0 2] (near atmospheric pressure), the ECM determines that the EVAP system has a large leakage, illuminates the MIL and sets the DTC (2 trip detection logic)
- P0456: EVAP very small leak
In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured If the stabilized system pressure is higher than the second reference pressure, the ECM determines that the EVAP system has a small leakage, illuminates the MIL and sets the DTC (2 trip detection logic)