This diagnostic tests the evaporative emission (EVAP) system for a small leak. The diagnostic runs when the ignition is in the OFF position, and the correct conditions are met. While the engine is operating, there are sources of heat transferred into the fuel tank from the following:
• | Exhaust heat |
• | Engine heat |
• | Ambient temperature |
When the engine is stopped and the ignition is in the OFF position, a change in the fuel tank vapor temperature occurs. This results in a change in the pressure of the fuel tank vapor space. This change in pressure is monitored by the control module, using the fuel tank pressure (FTP) sensor input. The EVAP diagnostic detects leaks as small as 0.51 mm (0.02 in). If the control module detects a change in the fuel tank vacuum/pressure less than a calibrated amount, this DTC sets.
This diagnostic procedure supports the following DTC:
DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected
Important: The following conditions must be met prior to the ignition OFF test.
• | DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0128, P0443, P0446, P0449, P0451, P0452, P0453, P0458, P0459, P0496, P0498, P0499, P0560, P0562, P0721, P0722, P0563, P0721, P0722, P2228, and P2229 are not set. |
• | The ignition 1 voltage is more than 10.8 volts. |
• | A refueling event is not detected. |
• | The fuel volatility is not excessive. |
• | The ambient air temperature (AAT) is between 2-32°C (35-90°F). |
• | The intake air temperature (IAT) is between 2-32°C (35-90°F) at start-up. |
• | The engine coolant temperature (ECT) is less than 42°C (108°F) at start-up. |
• | The ECT and the IAT are within 10°C (18°F) of each other at engine start-up. |
• | The barometric pressure (BARO) is more than 68 kPa. |
• | The engine coolant temperature (ECT) during the previous ignition was more than 74°C (165°F). |
• | The fuel level is between 12-88 percent. |
• | The vehicle traveled more than 8 km (5 mi) with vehicle speed above 2.5 km/h (1.6 mph). |
• | The engine run time is more than 10 minutes. |
• | DTC P0442 runs once per engine off cycle when the above conditions have been met prior to engine shut down. |
The control module detects approximately 8 vacuum/pressure changes significantly 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 MIL after approximately 6 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 an intermittent leak, use the J 41413-200 Evaporative Emission 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. Introducing smoke in 15-second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner. |
• | To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT . |
• | If it is necessary to plug the EVAP vent inlet to perform a leak test, the EVAP vent solenoid valve must be physically inspected to ensure its ability to seal the system. |
• | For an intermittent condition, 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 - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||||
2 |
Did you find and correct the condition? | Go to Step 5 | Go to Step 3 | ||||||||||
Note:
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 | ||||||||||
Note: 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 |
Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |