System Description
The diagnostic strategy for the evaporative emission (EVAP) system uses a vacuum pump to test for system leaks, after the engine is OFF. A unique fuel tank, EVAP canister, and EVAP vacuum leak pump work together to provide enhanced system diagnosis. The vacuum leak pump, the fuel tank pressure (FTP) sensor and the EVAP canister vent valve are all integral parts of one assembly. The assembly is attached directly to the EVAP canister, located near the fuel tank.
After the vehicle has sat with the engine OFF for about 5 hours, a comprehensive diagnostic is enabled with no operator input necessary. The complete test can take up to 15 minutes to run, with leak detection comprising the largest portion of the test. For more detailed information on the EVAP system components and diagnostic theory, refer to Evaporative Emission Control System Description .
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2401 Evaporative Emission (EVAP) System Leak Detection Pump Control Circuit Low Voltage
Conditions for Running the DTC
| • | DTCs P0110, P0112, P0113, P0115, P0117, P0118, P0450, P0451, P0452, P0453, P2610 are not set. |
| • | Five hours have elapsed after the engine was turned OFF. |
| • | Atmospheric pressure is between 70-110 kPa. |
| • | Battery voltage is more than 10.5 volts. |
| • | Engine coolant temperature (ECT) is between 4-35°C (40-95°F). |
| • | Intake air temperature (IAT) is between 4-35°C (40-95°F). |
| • | The ignition remains OFF for the duration of the test. |
| • | DTC P2401 runs once per drive cycle when the above conditions are met. |
Conditions for Setting the DTC
The powertrain control module (PCM) has determined the EVAP vacuum leak detection pump may be stuck OFF, because the specified vacuum pressure was not obtained.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present. |
| • | A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault. |
| • | A DTC can be cleared by using the scan tool Clear Information function. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If you had DTC P2419 set with DTC P2401, go perform the P2419 diagnostic procedure before continuing in this diagnostic table. If you are at this diagnostic table because you were sent here from DTC P2419, go to Step 7. If only DTC P2401 was set, also go to Step 7.
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This step uses the EVAP Service Bay test in order to verify the correct operation of the EVAP vent solenoid, the EVAP purge solenoid, and the EVAP vacuum leak pump. Using the Service Bay test also tests for leaks by sealing the system and monitoring the FTP sensor.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Did the test lamp illuminate? | Go to Step 3 | Go to Step 4 |
If a DTC P2419 was also set, did you already perform the P2419 diagnostic procedure? | Go to Step 7 | Go to DTC P2419 | |
4 | Connect a test lamp to B+ and the vacuum pump ground circuit. Does the test lamp illuminate? | Go to Step 5 | Go to Step 6 |
5 |
Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
6 | Repair the open in the vacuum pump ground circuit. Refer to Testing for Intermittent Conditions and Poor Connections . Did you complete the repair? | Go to Step 11 | -- |
7 |
Did you find and correct the condition? | Go to Step 11 | Go to Step 8 |
8 | Replace the EVAP vacuum leak pump assembly. Refer to Evaporative Emission System Vacuum Leak Pump Replacement . Did you complete the replacement? | Go to Step 11 | -- |
9 |
Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
10 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | -- |
Is DTC P2401 set in Last Test Failed? | Go to Step 2 | Go to Step 12 | |
12 |
Are there any DTCs that have not been diagnosed? | System OK | |
