Description
The EVAP large leak test applies vacuum to the evaporative emission (EVAP) system and monitors vacuum decay. The powertrain control module (PCM) monitors the fuel tank pressure (FTP) sensor signal to determine the vacuum decay rate. At an appropriate time, the PCM turns the EVAP canister purge valve ON (open) and the EVAP vent valve ON (closed). This allows the engine to draw a vacuum on the EVAP system. At a calibrated time, or vacuum level, the PCM turns the purge valve OFF (closed), sealing the system, and monitors the FTP sensor input in order to determine EVAP system vacuum. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, DTC P0440 will set.
Conditions for Running the DTC
| • | DTC P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0452, or P0453 are not set. |
| • | The ignition voltage is between 10 and 18 volts. |
| • | The barometric pressure is more than 75 kPa. |
| • | The fuel level is between 15 and 85 percent. |
| • | The engine coolant temperature (ECT) is between 4°C and 30°C (39°F and 86°F). |
| • | The intake air temperature (IAT) is between 4°C and 30°C (39°F and 86°F). |
| • | The start up ECT and IAT are within 9°C (16°F) of each other. |
| • | The vehicle speed sensor (VSS) is less than 121 km/h (75 mph). |
Conditions For Setting the DTC
The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test ran and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the malfunction indicator lamp (MIL) OFF during the first consecutive trip in which the diagnostic has been run and passed. |
| • | A last test failed (current DTC) clears when the PCM turns OFF the MIL. |
| • | The history DTC will clear after the PCM runs and passes 40 consecutive warm up cycles with no failure. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
| • | Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition. |
| • | Use the EVAP pressure/purge diagnostic station in order to pressurize the EVAP system to aid in locating intermittent leaks. Move all EVAP components while testing with the ultrasonic leak detector. |
| • | A temporary blockage in the EVAP canister purge valve, purge pipe or EVAP canister could cause an intermittent condition. To repair a blockage in the EVAP system refer to Fuel System Cleaning . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This test verifies that the EVAP purge valve is electrically functional.
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This test verifies that the EVAP vent valve is electrically functional.
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This test verifies that engine vacuum is present when the EVAP purge valve is open.
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This test verifies that the FTP sensor is accurate. An EVAP FTP sensor that does not correctly respond to vacuum (or pressure) may cause this DTC to set.
Step | Action | Values | Yes | No | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Emission Hose Routing Diagram | ||||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||||||||
2 | Are DTCs P0446, P0452, P0453, or P1441 also set? | -- | Go to Step 3 | |||||||||||||||||||||
3 | Inspect the EVAP system for the following conditions:
Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 4 | ||||||||||||||||||||
Do you hear or feel a clicking from the EVAP purge valve when it is commanded to 50 percent? | -- | Go to Step 5 | Go to Step 6 | |||||||||||||||||||||
With the scan tool, command the EVAP canister vent valve ON and OFF. Do you hear or feel a click as the EVAP vent valve is commanded ON and OFF? | -- | Go to Step 10 | Go to Step 8 | |||||||||||||||||||||
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 22 | ||||||||||||||||||||
7 |
Does the test lamp illuminate when the EVAP purge valve is commanded to 50 percent and turn OFF when the EVAP purge valve is commanded to 0 percent? | -- | Go to Step 18 | Go to Step 16 | ||||||||||||||||||||
8 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 23 | ||||||||||||||||||||
9 |
Does the test lamp illuminate when the EVAP vent valve is commanded ON? | -- | Go to Step 19 | Go to Step 17 | ||||||||||||||||||||
Is the vacuum at or more than the specified value? | 15 in H2O | Go to Step 11 | Go to Step 21 | |||||||||||||||||||||
11 |
Important: The following steps require the J 41413 EVAP pressure/purge diagnostic station, and the J 41415-40 fuel tank cap adaptor. Always zero the EVAP pressure and vacuum (in H2O) gauges on the EVAP pressure/purge diagnostic station before proceeding with the diagnosis.
Were you able to obtain and hold the specified value for 1 minute? | 5 in H2O | Go to Step 12 | Go to Step 13 | ||||||||||||||||||||
Compare the EVAP diagnostic station pressure gauge value to the scan tool fuel tank pressure (FTP) sensor value. Does the EVAP pressure/purge diagnostic station gauge value correspond to the FTP sensor value on the scan tool? | -- | Go to Step 14 | Go to Step 29 | |||||||||||||||||||||
13 |
Important: It may be necessary to partially lower the fuel tank to inspect the components located in the upper portion of the tank.
Did you find and repair the condition? | -- | Go to Step 31 | Go to Diagnostic Aids | ||||||||||||||||||||
14 |
Does the EVAP pressure/purge diagnostic station gauge decrease to near the specified value? | 0 in H2O | Go to Step 24 | Go to Step 15 | ||||||||||||||||||||
15 |
Does the EVAP pressure/purge diagnostic station gauge decrease to near the specified value? | 0 in H2O | Go to Step 28 | Go to Step 25 | ||||||||||||||||||||
16 | Test the control circuit of the EVAP purge valve for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 20 | ||||||||||||||||||||
17 | Test the control circuit of the EVAP vent valve for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 20 | ||||||||||||||||||||
18 | Test for poor connections at the harness connector of the EVAP purge valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 26 | ||||||||||||||||||||
19 | Test for poor connections at the harness connector of the EVAP vent valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 27 | ||||||||||||||||||||
20 | Test for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 30 | ||||||||||||||||||||
21 | Inspect the vacuum source to the EVAP purge valve for blockage, cuts, or disconnects. Repair as necessary. Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 26 | ||||||||||||||||||||
22 | Repair the ignition voltage circuit of the EVAP purge valve for an open or short to ground. Refer to Wiring Repairs in Wiring Systems. Replace the fuse as necessary. Did you complete the repair? | -- | Go to Step 31 | -- | ||||||||||||||||||||
23 |
Did you complete the repair? | -- | Go to Step 31 | -- | ||||||||||||||||||||
24 | Repair the restriction in the EVAP purge pipe. Refer to Evaporative Emission System Cleaning . Did you complete the repair? | -- | Go to Step 31 | -- | ||||||||||||||||||||
25 | Repair the restriction in the EVAP vapor pipe. Did you complete the repair? | -- | Go to Step 31 | -- | ||||||||||||||||||||
26 | Replace the EVAP purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||||||||||||||||
27 | Replace the EVAP vent valve. Refer to Evaporative Emission Canister Vent Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||||||||||||||||
28 | Replace the EVAP canister. Refer to Evaporative Emission Canister Replacement . Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||||||||||||||||
29 | Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||||||||||||||||
30 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 31 | -- | ||||||||||||||||||||
31 |
Does the EVAP system pressure remain constant? | -- | Go to Step 32 | Go to Step 4 | ||||||||||||||||||||
32 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||||||||||||
