P0440 General Evap System Failure

P0440 General Evap System Failure - The evap system was unable to archive or maintain vacuum during the test period or the system was not able to close the ESIM switch when vacuum was present.

After engine start up and the ESIM switch did not close during a previous ignition off event that eas valid. Must be a cold start and the following are true :

• The difference between the ECT and AAT inputs is less than 10°C (19°F).
• Fuel level between 12% and 88%.
• Manifold vacuum greater than a calculated minimum value.
• Ambient temperature between 4°C and 35°C (40°F and 95°F).

Default actions:

The MIL light illuminate

Possible causes:

• Evap purge solenoid vacuum supply
• Evap purge tube obstruction.
• Obstruction in the vent hose or filter.
• ESIM signal circuit open.
• ESIM sensor ground circuit open.
• ESIM orientation or installed incorrectly.
• Large evaporative emission leak.
• Evaporative system integrity monitor (ESIM) switch.
• Evap purge solenoid.
• Powertrain Control Module (PCM).

Diagnose code P0440 General Evap System Failure

Step 1. Check for active condition

Diagnose and repair any purge system or purge solenoid circuit DTCs before continuing with this test procedure. A hot vehicle may conceal a potential leak. For best results, allow the vehicle to cool to ambient temperature before continuing with this procedure.

If the customer is experiencing an early fuel shut off during the fuel filling process in addition to DTC P0440, P0441, or P0452, check for restrictions in the tubes/hoses between the Fuel tank and Evaporative Canister, ESIM , and the ESIM Vent Filter before continuing.

Turn the ignition on, using the scan tool, navigate to system test and start the ESIM forced monitor test. Allow the test to run until finished. Read the large leak test results. This is a test of the overall operation of the evaporative system components. It does not necessarily indicate that a large leak was the failure.

Did the large leak test pass or fail?

Passed, go to step 2.

Failed, go to step 3.

Step 2. Evap system inspection

If the switch is not in the proper orientation, it may cause the weighted pressure and vacuum vents to intermittently not seal correctly. The ESIM wiring harness connector should be in the 3 O’clock position.

Turn the ignition off, the condition that caused the fault is intermittent and not present at this time. perform a visual inspection of the entire evaporative emission system for any the following conditions:

• Proper orientation of the ESIM switch wiring connector (3 O'clock position).
• Holes or cracks.
• Loose seal points.
• Damaged or missing components.
• Incorrect routing of hoses and tubes.
• Loose or missing fuel filter cap (if applicable) or seal.
• Damaged seal points on the fuel filter cap (if applicable) or capless fuel filter assembly.
• Ice or intermittent blockage in the ESIM vent filter or hose.

Were any problems found?

YES, repair as necessary.

NO, testing complete.

Step 3. Evap purge solenoid vacuum supply hose inspection

Inspect the purge solenoid vacuum supply hose for proper routing and installation. Check for a pinched or plugged hose between the throttle body or intake manifold and the purge solenoid. Make sure the vacuum port at the throttle body or intake manifold is free from any contamination, obstruction, or blockage.

Were any problems found?

YES, repair as necessary.

NO, go to step 4.

Step 4. Evap purge solenoid

Warning: Keep lit cigarettes, sparks, flames, and other ignition sources away from the test area to prevent the ignition of explosive gases. Keep the test area well ventilated. Failure to do so may result in possible serious or fatal injury.

After disconnecting the Evap Purge Solenoid vacuum connections, inspect the lines and solenoid for signs of contamination.

Disconnect both vacuum hoses at the evap purge solenoid. Using a hand vacuum pump, apply 5 in.hg to the engine side of the evap purge solenoid. Start the engine, using the scan tool, navigate to system test and start the purge vapors system test. Select open to actuate the purge solenoid to the ON position. The vacuum should drop when the purge solenoid is actuated.

Does the solenoid function as described above?

YES, go to step 5.

NO, Verify that there is good pin to terminal contact at the Evap Purge Solenoid and PCM harness 

connectors. Replace the Evap Purge Solenoid if no problems were found in the connectors.

Step 5. ESIM switch state

Turn the ignition off, attach the hand vacuum pump into the hose leading to the evaporative canister. Turn the ignition on, using the hand vacuum pump, apply vacuum and monitor the fuel tank pressure sensor reading and the ESIM switch state with the scan tool. Normally, the Fuel Tank Pressure Sensor should read approximately -0.7 psi and the ESIM Switch should display as closed on the scan tool. The reading should remain stable with no fluctuations.

Which of the following conditions are present?

ESIM switch open and fuel tank pressure sensor DOED NOT read negative PSI or vacuum, go to step 10.

ESIM switch open and fuel tank pressure sensor DOES read negative PSI or vacuum, go to step 6.

Step 6. Check the ESIM switch

Disconnect the ESIM swith harness connector. Using the scan tool, read the ESIM switch state. Connect a jumper between the ESIM signal circuit and the ground circuit at the ESIM switch harness connector. Using the scan tool, read the ESIM switch state.

Does the ESIM switch state change from OPEN when disconnected to CLOSED when the jumper is installed?

YES, replace the ESIM.

NO, go to step 7.

Step 7. Check the ESIM signal circuit for an open/high resistance

Turn the ignition off, disconenct the PCM harness connector. Measure the resistance of the ESIM signal circuit between the ESIM switch harness connector and PCM harness connector.

Is the resistance below 5.0 Ohms?

YES, go to step 8.

NO, repair the ESIM signal circuit for an open or high resistance.

Step 8. Check the ground circuit for an open/high resistance

Measure the resistance between ground and the ground circuit at the ESIM switch harness connector.

Is the resistance below 5.0 Ohms?

YES, go to step 9.

NO, repair the ground circuit for an open or high resistance.

Step 9. Powertrain Control Module (PCM)

Using the wiring diagram as a guide, inspect the wiring and conenctors between the ESIM switch and the PCM. Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Perform any Technical service bulletins that may apply.

Were any problems found?

YES, repair as necessary.

NO, replace and program the PCM. Perform the PCM verification Test.

Step 10. Evap purge hose/tube and vent filter obstruction

Disconnect the tube and vent filter from the ESIM. Using the hand vacuum pump, apply vacuum and monitor the fuel tank pressure sensor reading and the ESIM switch state with the scan tool.

Did the ESIM switch close?

YES, repair the obstruction in the vent tube or filter.

NO, go to step 11.

Step 11. Evaporative emission leak detection

Warning: Keep lit cigarettes, sparks, flames, and other ignition sources away from the test area to prevent the ignition of explosive gases. Keep the test area well ventilated. Failure to do so may result in possible serious or fatal injury.

To continue testing, you will need the evaporative leak detector (EELD). Connect the red power lead of EELD to the battery positive terminal and the black ground lead to battery negative terminal. Connect shop air to the EELD. Remove the ESIM vent filter and install the appropriate smoke machine. The exiting smoke deposits a residual fluid that is either bright green or bright yellow in color when viewed with a UV light.

Select the appropriate response from the list below?

A leak was found at the fuel cap (if applicable) or fuel filter tube assembly, perform the appropriate repair by replacing the fuel filter tube assebly and / or the fuel cap (if applicable). Run the ESIM forced monitor test again to verify the repair is complete.

A leak was found in the evaporative system, if the leak is at a hose connection, remove the hose, then reconnect the hose and check for a leak again. All other leaks, repair as necessary. Run the ESIM forced monitor test again to verify the repair is complete.

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