P0441

DTC P0441

SYSTEM DESCRIPTION
The DTC P0441 Evaporative Emission (EVAP) System No Flow During Purge diagnostic monitors the changes in the vacuum pressure in the fuel tank. The diagnostic strategy for the 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. If the powertrain control module (PCM) detects the vacuum level was not achieved, DTC P0441 will set. For more detailed information on the EVAP system components and diagnostic strategy, refer to Evaporative Emission (EVAP) Control System Description.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0441 Evaporative Emission (EVAP) System No Flow During Purge

CONDITIONS FOR RUNNING THE DTC
- DTC P0011, P0012, P0100, P0101, P0102, P0103, P0110, P0112, P0113, P0115, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0300, P0301-P0304, P0335, P0340, P0341, P0351-P0354, P0385, P0450, P0451, P0452, P0453, P0500 are not set.
- Battery voltage is more than 10 volts.
- The engine is running.
- The engine coolant temperature (ECT) is more than 5°C (40°F).
- The intake air temperature (IAT) is more than 5°C (40°F).
- DTC P0441 runs once per drive cycle when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The FTP sensor does not detect the expected decrease in pressure when the EVAP canister purge valve is ON.
OR
The pressure change when the EVAP canister vent solenoid is turned ON during a purge event, is less than the expected value.

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.

DIAGNOSTIC AIDS
- If DTC P0441 is the only EVAP DTC set, the most likely cause is a malfunctioning EVAP canister purge valve. Inspect the EVAP canister purge valve carefully for faulty connections and erratic operation.
- The information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set. If the Freeze Frame data indicates the engine was not running when the diagnostic ran and failed, the fault is probably a leak in the EVAP system. Refer to DTC P0455. P0455
- A faulty EVAP canister can cause a DTC P0441 and P0455 to set. Test the EVAP canister for internal passage leaks and restrictions. Also test the canister for the correct operation of diaphragms, check balls, and internal valves. Refer to Evaporative Emission (EVAP) Control System Diagnosis. Evaporative Emission (EVAP) Control System Diagnosis
- An intermittent malfunction may be caused by a fault in any of the EVAP solenoid electrical circuits. Inspect the wiring harness and components for an intermittent condition.

TEST DESCRIPTION

Step 1 - Step 12:

Step 13 - Step 21:

The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that the DTC P0441 is captured in the Freeze Frame/Failure Record list. When multiple EVAP system DTCs are set, the DTC stored in the Freeze Frame/Failure Record is the best diagnostic starting point.
3. This step verifies the electrical operation of the EVAP canister purge solenoid.
4. This step tests the function of the EVAP canister purge solenoid.
7. This step uses the EVAP Service Bay test in order to verify the correct operation of the EVAP canister purge solenoid and the other EVAP system components. Performing the EVAP Service Bay test also tests for EVAP system leaks. Service Bay Test
18. This step tests for a blockage or a restriction in the purge port and purge passages located in the EVAP canister assembly. If the purge passage is blocked or restricted, the EVAP system diagnostic can fail and set this DTC.
19. This step uses the EVAP Service Bay test in order to verify the correct operation of the EVAP canister purge solenoid and the EVAP vacuum leak pump assembly. Performing the EVAP Service Bay test also tests for EVAP system leaks. Service Bay Test