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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- P043E: 0.02 inch orifice clogged
In operation B, the vacuum pump creates negative pressure (vacuum) through the 0.02 inch orifice. The EVAP system pressure is then measured by the ECM, using the pressure sensor, to determine the 0.02 inch leak pressure standard. If the pressure is lower than -4.3 kPa (-32.25 mmHg)*, the ECM interprets this as a clog malfunction in the 0.02 inch orifice, and stops the EVAP (Evaporative Emission) system monitor. The ECM then illuminates the MIL and sets the DTC (2 trip detection logic).
*: 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.
- P043F: 0.02 inch orifice high-flow
In operation B, the vacuum pump creates negative pressure (vacuum) through the 0.02 inch orifice. The EVAP system pressure is then measured by the ECM using the pressure sensor to determine the 0.02 inch leak pressure standard. If the pressure is higher than -1.2 kPa (-9.0 mmHg)*, the ECM interprets this as a high-flow malfunction in the 0.02 inch orifice, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (2 trip detection logic).
*: The threshold varies according to the atmospheric pressure measured in operation A. The value described above is based on a atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.