Monitor Description
5 hours after the ignition switch is turned to OFF, the electric vacuum pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.
| Sequence | Operations | Descriptions | Duration | ||
|---|---|---|---|---|---|
| - | ECM activation | Activated by soak timer, 5 hours after ignition switch turned to 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 pressure standard, negative pressure (vacuum) created through 0.02 inch orifice and then EVAP system pressure measured by ECM. | 60 seconds | ||
| C | EVAP leak check | Vent valve turned ON (closed) to shut EVAP system. | 12 minutes(1) | ||
| C | EVAP leak check | Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then measured. | 12 minutes(1) | ||
| C | EVAP leak check | If stabilized system pressure higher than 0.02 inch leak pressure standard, ECM determines that EVAP system leaking. | 12 minutes(1) | ||
| C | EVAP leak check | If EVAP pressure does not stabilize within 12 minutes, ECM cancels EVAP system monitor. | 12 minutes(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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- P0455: EVAP (Evaporative Emission) gross leak
In operation C, the vacuum pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than [0.02 inch leak pressure standard 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 vacuum pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than 0.02 inch leak pressure standard, the ECM determines that the EVAP system has a small leakage, illuminates the MIL and sets the DTC (2 trip detection logic).