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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- P2419: Vent valve stuck ON
In operation B, the vacuum pump creates negative pressure (a vacuum) through the 0.02 inch orifice. The EVAP (Evaporative Emission) system pressure is then measured by the ECM, using the pressure sensor, to determine the 0.02 inch leak pressure standard. If the pressure exceeds -1.2 kPa (-9.0 mmHg)* 4 seconds after the vacuum pump is turned ON, the ECM interprets this as the vent valve being stuck ON. The ECM illuminates the MIL and sets the DTC.
*: The threshold varies according to the atmospheric pressure measured in operation A. The value described above is based on an atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.
- P2420: Vent valve stuck OFF
In operation C, the vent valve turns ON (closes) and the EVAP (Evaporative Emission) system pressure is then measured by the ECM, using the pressure sensor, to conduct an EVAP leak check. If the pressure does not increase by more than 0.3 kPa (2.25 mmHg) within 10 seconds of the vent valve being turned from OFF (vent) to ON, the ECM interprets this as the vent valve being stuck OFF. The ECM illuminates the MIL and sets the DTC.