System Inspection

Caution: Do not breathe the air through the EVAP component tubes or hoses. The fuel vapors inside the EVAP components may cause personal injury.

Important: Perform a careful visual inspection of the EVAP control system components and connecting hoses before the diagnosis of an EVAP control system malfunction.

1. Allow the engine to cool to room temperature.
2. Start the engine (cold).
3. Disconnect the purge hose (1) from the EVAP canister purge valve (2).
4. Place a finger against the end of the disconnected hose and check for vacuum. Vacuum should not be felt when the engine is below normal operating temperatures.
5. Connect the purge hose to the EVAP canister and warm the engine up to normal operating temperature.
6. Disconnect the purge hose (1) from the EVAP canister purge valve (2).

Important: The EVAP control system does not perform EVAP canister purging (vacuum is not detected at the purge hose) unless the engine is sufficiently warmed up and the heated oxygen sensor (HO2S) is fully activated. When the purge hose is disconnected as in step 6, some air may be drawn into the purge line. As a result, the powertrain control module (PCM) might detect a change in the purge gas concentration and stop purging. This is a normal action and may be the cause of a failure to detect vacuum in step 7. If no vacuum is felt in step 7, continued testing of the EVAP system may be necessary in order to avoid the replacement of good parts.

7. Place a finger over the disconnected hose and check for vacuum. Vacuum should be felt with the engine running at normal operating temperature.

Failure of the EVAP control system to pass any of these checks indicates a possible malfunction that will require further inspection.