This diagnostic tests the evaporative emission (EVAP) system for a small leak when the ignition is turned OFF, and the correct conditions are met.
Heat from the exhaust system is transferred into a vehicle fuel tank while the vehicle is operating. When the ignition is turned OFF, a change in the fuel tank vapor temperature occurs. With the EVAP system sealed, this results in corresponding pressure changes in the fuel tank vapor space. This change is monitored by the control module using the fuel tank pressure sensor input. The control module then makes a judgement on the integrity of the system. With a 0.51 mm (0.020 inches) leak in the system, the amount of pressure change observed is significantly less than that of a sealed system.
If the control module detects a pressure change less than a calibrated amount, DTC P0442 sets.
• | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0335, P0336, P0341, P0351, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P0500, P0502, P0503, P1106, P1107, P1683 are not set. |
• | The diagnostic runs once with a 10 hour minimum between tests after a fail. |
• | DTC P0455 must run and pass. |
• | The start up intake air temperature (IAT) is between 4-30°C (39-86°F). |
• | The start up engine coolant temperature (ECT) is less than 30°C (86°F). |
• | The start up IAT and ECT are within 8°C (15°F). |
• | The barometric pressure (BARO) is more than 74 kPa. |
• | The ambient air temperature is between 2-32°C (36-90°F). |
• | The engine run time minimum is 10 minutes. |
• | The odometer displays more than 10 miles. |
• | The vehicle has traveled more than 3 miles this trip. |
• | The ECT is more than 70°C (158°F). |
• | The fuel level is between 15-85 percent. |
• | The ignition is OFF. |
The control module detects a pressure change that is less than a calibrated amount.
• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Clear the MIL and the DTC with a scan tool. |
• | To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. |
• | To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT . |
• | A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool Purge/Seal function to create a vacuum, seal the system and observe the FTP parameter for vacuum decay, this type of leak may be detected. |
• | For intermittent conditions, refer to Intermittent Conditions . |
The numbers below refer to the step numbers on the diagnostic table.
Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
This step verifies that repairs are complete and that no other condition is present.
Step | Action | Yes | No |
---|---|---|---|
Schematic Reference: Evaporative Emissions Hose Routing Diagram | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 |
Important: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.
Is the floating indicator below the red flag? | Go to Diagnostic Aids | Go to Step 3 |
Important: Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. System flow will be less with higher temperatures.
Did you locate and repair a leak source? | Go to Step 5 | Go to Step 4 | |
4 |
Did you locate and repair a leak source? | Go to Step 5 | Go to Diagnostic Aids |
Important: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.
Is the floating indicator below the red flag? | Go to Step 6 | Go to Step 2 | |
6 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK |