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.

Fig 1: Monitor Description Chart

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Fig 2: EVAP Leak And Pressure Measurement Checking System Diagram (A-D)

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1. P2401: Vacuum pump stuck OFF

   For order C, the vacuum pump creates negative pressure (vacuum) through the 0.02 inch orifice and pressure is measured. If the pressure is higher than -7.5 mmHg (-1 kPa) or lower than -33.75 mmHg (-4.5 kPa), the ECM determines that the vacuum pump is stuck OFF (has not operated). The ECM illuminates the MIL and sets DTC (2-trip detection logic).

Fig 3: EVAP Pressure Leak Graph (Vacuum Pump Stuck Off)
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2. P2402: Vacuum pump stuck ON

   If the difference in EVAP system pressure for order A and C is small and is higher than -7.5 mmHg (-1 kPa), ECM determines that the vacuum pump is stuck ON (has been operating throughout order A to C). The ECM illuminates the MIL and sets DTC (2-trip detection logic).

Fig 4: EVAP Pressure Leak Graph (Vacuum Pump Stuck On)
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