EVAP system leak inspection using WDS or equivalent

WARNING: This page is about a different car, the 2005 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: EVAP system test outline

The EVAP system test, which can substituted for the run drive cycle as an EVAP control system repair confirmation method, can be done while operating the WDS in the KOEO (Key On Engine Off) condition instead of actually driving the vehicle.

EVAP system test description

The EVAP system test finds gas leaks in the system using the PCM to monitor changes in the air pump load current of the EVAP system leak detection pump. This test starts after sending an on-demand test signal from the WDS to the PCM. The PCM controls the air pump and change-over-valve operation and also stores the load current of the air pump as follows:
1. The PCM commands turn the air pump on and retrieve the air pump load current value (LDP_MON PID) as a reference current (LDP_REF PID).
2. After retrieving a reference current value, the PCM commands the change-over-valve to open, then captures the air pump load current value (LDP_MON PID) as idle current (LDP_IDL PID). The EVAP system will be pressurized from this phase.
3. The PCM continues to monitor the air pump load current value (LDP_MON PID) until the end of the test.
Fig 1: Identifying EVAP System Test Graph
Courtesy of MAZDA MOTORS CORP.
You can confirm whether any evaporative gas leak occurred or not by reading the test results.

Fig 2: Identifying Evaporative Gas Leak Testing Diagram
Courtesy of MAZDA MOTORS CORP.

EVAP system malfunction judgment

The WDS calculates the stored air pump load current value and displays the results as follows:
- Small leak results (DTC P0442) = LDP_SLDV
- Very small leak results (mA/S: DTC P0456) = LDP_VSLDV
- Very small leak results (mA: DTC P0456) = LDP_REF-LDP_MON (when test ended)
- IMO result (air pump operation) = LDP_MON (when test ended)
- COV result (change-over-valve statues) = LDP_REF -LDP_IDL