This DTC tests the evaporative emission (EVAP) system for a small leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the vacuum decay rate. At an appropriate time, the control module turns the EVAP canister purge valve ON and the EVAP vent valve ON. This allows the engine to draw a vacuum on the EVAP system. At a calibrated time, or vacuum level, the control module turns the EVAP canister purge valve OFF, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum decay. If the control module detects a leak larger than a calibrated amount, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent valves.
Control Module Command | EVAP Canister Purge Valve | EVAP Canister Vent Valve |
---|---|---|
ON | Open | Closed |
OFF | Closed | Open |
• | DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1106, P1107, P1112, P1114, P1115, P1121, or P1122 are not set. |
• | The system voltage is between 10-18 volts. |
• | The engine coolant temperature (ECT) is between than 4-30°C (39-86°F). |
• | The intake air temperature (IAT) is between than 4-30°C (39-86°F). |
• | The fuel tank level is between 15-85 percent. |
• | The barometric pressure (BARO) is more than 75 kPa. |
• | The vehicle speed sensor (VSS) is less than 121 km/h (75 mph). |
• | The start-up ECT and IAT are within 9°C (16°F). |
The EVAP system can achieve vacuum but a vacuum decay is detected during the diagnostic test.
• | 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 aid in locating intermittent leaks, use the J 41413 EVAP Pressure and Purge Station to pressurize the EVAP system. Move all EVAP components while testing with the J 41416 Ultrasonic Leak Detector.
The numbers below refer to the step numbers on the diagnostic table.
This step verifies that a failure condition is active.
This step verifies that repairs are complete and that no other condition is present.
Step | Action | Values | Yes | No | ||||||||||||||||||||
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Schematic Reference: Evaporative Emissions Hose Routing Diagram | ||||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||||||||
2 | Does the scan tool indicate DTC P0443 or DTC P0449 are also set? | -- | Go to Step 3 | |||||||||||||||||||||
3 |
Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 4 | ||||||||||||||||||||
Does the scan tool indicate that the Service Bay Test passed? | -- | Go to Diagnostic Aids | Go to Step 5 | |||||||||||||||||||||
5 |
Important: Always zero the EVAP pressure and vacuum (in H2O) gages on the EVAP pressure diagnostic station before proceeding with diagnosis.
Important: It may be necessary to partially lower the fuel tank to inspect components located in the upper portion of the tank.
Did you find and correct the condition? | Go to Step 6 | Go to Diagnostic Aids | |||||||||||||||||||||
Does the scan tool indicate that the Service Bay Test passed? | -- | Go to Step 7 | Go to Step 5 | |||||||||||||||||||||
7 | With a scan tool, observe the stored information, Capture Info. with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? | System OK |