Monitor Description
5 hours* after the ignition switch is turned OFF, the electric leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) 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 | Activated by soak timer 5, 7 or 9.5 hours after ignition switch OFF. | - | ||
| A | Atmospheric pressure measurement | Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to register atmospheric pressure. If EVAP pressure does not reach between 70 kPa and 110 kPa (525 mmHg and 825 mmHg), ECM cancels EVAP system monitor. |
10 seconds | ||
| B | 0.02 inch leak pressure measurement | In order to determine 0.02 inch leak criterion, negative pressure (vacuum) created through reference orifice and then EVAP system pressure measured by ECM. | 60 seconds | ||
| C | EVAP leak check | Vent valve turned ON (closed) to shut EVAP system. Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then measured. If stabilized system pressure higher than 0.02 inch leaks criterion, ECM determines that EVAP system leaking. If EVAP pressure does not stabilize within 720 seconds, ECM cancels EVAP system monitor. |
720 seconds(1) | ||
| D | Purge VSV monitor | Purge VSV opened and then EVAP system pressure measured by ECM. Large increase indicates normal. |
10 seconds | ||
| E | Final check | Atmospheric pressure measured and then monitoring result recorded by ECM. | - | ||
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In sequence B, to determine the leak criterion, the leak detection pump creates negative pressure in the canister pump module through the reference orifice. If the pressure is out of specified range or is not saturated, the ECM illuminates the MIL and sets DTCs P043E, P043F, P2401, P2402 and P2419 (2-trip detection logic).