Monitor Description
When 5 hours have elapsed after the ignition switch is turned OFF, the electric vacuum pump creates negative pressure (vacuum) in EVAP system. Then ECM monitors for leaks and actuator malfunctions based on EVAP pressure.
| Order | Operation | Description | Time | ||
|---|---|---|---|---|---|
| - | ECM start | Power is supplied to ECM when 5 hours have passed after ignition switch is turned OFF. | - | ||
| A | Atmospheric pressure measurement | ECM turns vent valve OFF (vent) and measures EVAP system pressure to memorize atmospheric pressure. If EVAP pressure is not 525 to 825 mmHg (70 to 110 kPa), ECM cancels EVAP monitor. | 10 seconds | ||
| B | EVAP volume measurement | ECM turns vent valve ON (closed) to close EVAP system. ECM measures EVAP pressure to check EVAP volume. If pressure is not stable, ECM interprets that EVAP volume is too large to continue EVAP monitor and cancels EVAP monitor. | 60 seconds | ||
| C | 0.02 inch leak pressure measurement | Vacuum pump creates negative pressure (vacuum) through 0.02 inch orifice and pressure is measured. ECM determines this as 0.02 inch leak pressure. | 60 seconds | ||
| D | EVAP leak check | Vacuum pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure is measured. If stabilized pressure is larger than 0.02 inch leak pressure, ECM determines EVAP system has leak. If EVAP pressure does not stabilize within 12 minutes, ECM cancels EVAP monitor. | Within 12 minutes(1) | ||
| E | Check valve monitor | ECM stops vacuum pump and measures EVAP pressure increase. If there is no increase, ECM interprets this as normal. | 10 seconds | ||
| F | Purge VSV monitor | ECM opens purge VSV and measures EVAP pressure increase. If increase is large, ECM interprets this as normal. | 10 seconds | ||
| G | Final check | ECM measures atmospheric pressure and records monitor result. | - | ||
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- P0455: EVAP gross leak
For order D, the vacuum pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure is measured. If the stabilized pressure is larger than "(0.02 inch leak pressure) x 0.2" (near atmospheric pressure), the ECM determines that the EVAP system has a large leakage, illuminates the MIL and sets a DTC (2-trip detection logic).
- P0456: EVAP small leak
For order D, the vacuum pump creates negative pressure (vacuum) in EVAP system and EVAP system pressure is measured. If the stabilized pressure is larger than 0.02 inch leak pressure, the ECM determines that the EVAP system has a small leakage, illuminates the MIL and sets a DTC (2-trip detection logic).