Monitor Description
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.
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.
| Sequence | Operation | Description | Duration |
|---|---|---|---|
| - | ECM activation | The key-off monitor is activated by soak timer 5, 7 or 9.5 hours after ignition switch turned off. | - |
| A | Atmospheric pressure measurement | Vent valve is turned OFF (vent) and the EVAP system pressure is measured by ECM in order to register atmospheric pressure. If pressure in EVAP system is not between 70 kPa-a and 110 kPa-a (525 mmHg-a and 825 mmHg-a), the ECM cancels EVAP system monitor. |
60 seconds |
| B | First reference pressure measurement | In order to determine reference pressure, the leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if the leak detection pump and vent valve operate normally. | 60 seconds |
| C | EVAP system pressure measurement | Vent valve turned ON (closed) to shut the EVAP system. Negative pressure (vacuum) created in the EVAP system, and EVAP system pressure then measured. The measured value is memorized as it will be used in the leak check. If the EVAP pressure does not stabilize within 15 minutes, the ECM cancels EVAP system monitor. |
15 minutes* |
| D | Purge VSV monitor | Purge VSV is opened and then the EVAP system pressure is measured by the ECM. A large increase indicates normality. |
10 seconds |
| E | Second reference pressure measurement | After a second reference pressure measurement, the leak check is performed by comparing the first and second reference pressure. If stabilized system pressure is higher than second the reference pressure, the ECM determines that the EVAP system is leaking. |
60 seconds |
| - | Final check | Atmospheric pressure is measured and then the monitor result is recorded by the ECM. | - |
*: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.
- (a) 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 leak, illuminates the MIL and sets the DTC (2 trip detection logic).
- (b) 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 leak, illuminates the MIL and sets the DTC (2 trip detection logic).