NGC

P0441-EVAP PURGE SYSTEM PERFORMANCE





For a complete wiring diagram Consult Diagrams/Electrical.

Theory of Operation

The Evap Purge Monitor tests the integrity of the hoses/tube between the throttle body/intake and the fuel tank. The monitor is a two stage test and runs only after the Evap system passes the small leak test. Stage one is non-intrusive. The PCM monitors the purge vapor ratio and the ESM switch closed ratio. If the purge vapor ratio is above a calculated value, the monitor passes. If the ESM switch closed ratio is greater than calculated value when purge flow is greater than a minimum value, the monitor passes. Stage two is an intrusive test and runs only if stage one does not pass. The PCM commands the purge solenoid to flow at a specified rate to force the purge vapor ratio to update. The ratio is compared to a calibrated specification. If the ratio is less than the specification, a one trip failure is recorded. This test can detect if the purge hose is off, obstructed, or the purge valve is not operational.

- When Monitored:
After the Evap System small leak test has passed, with the engine running, ambient temperature between 4° C (39° F) and 35° (95° F), with the engine at idle after a calibrated amount of drive time has accumulated.

- Set Condition:
If the PCM detects that the purge vapor ratio and the ESM switch closed ratio are below a calculated value, the PCM commands the purge solenoid to flow at a specified rate to update the purge vapor ratio. If the ratio remains below a specified value, a one trip failure is recorded. Two Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION
Ignition on, engine not running.
With a scan tool, select View DTCs. Record the Freeze Frame data if any DTCs are present.
Whether or not any DTC(s) are Active you will want to check the following items which may assist in repairing the customer's complaint successfully.
Check the vehicle's repair history.
If the vehicle has a repair history that pertains to the customer's current complaint, review the repair.
Inspect the vehicle for any aftermarket accessories that may have been installed incorrectly.
Check for any service bulletin(s) related to the customer's complaint or DTC(s).
If a service bulletin applies, follow the instructions per the service bulletin.
Choose the following scenario that best applies.

The service bulletin repaired the customer's complaint.

- Testing complete.

A DTC is present, no service bulletins apply, or the service bulletin didn't repair the customer's complaint.

- Go to 2

2. ACTIVE DTC
NOTE: If P0443 is set along with this DTC, perform the diagnostic procedure for P0443 before continuing with this test.

NOTE: If the customer is experiencing an early fuel shut off during the fuel filling process along with P0440, P0441, and P0452 setting, you need to check for restrictions in the EVAP Purge tubes/hoses as well as the Fresh Air Filter before continuing.

Start the engine.
Allow the engine to idle.
Using the scan tool, perform the ESIM FORCED MONITOR TEST. Allow the test to complete.
With a scan tool, select View DTCs.

NOTE: If any other DTC sets, active or pending, perform the diagnostic procedure for that DTC before proceeding with this test.

Is the DTC Active at this time?

Yes

- Go to 3

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking For An Intermittent DTC

3. EVAP SYSTEM INSPECTION
Inspect the Evap System for any of the following conditions:
- Holes or cracks
- Loose seal points
- Damaged or missing components
- Incorrect routing of hoses and tubes
- Loose or missing Fuel Cap
- Damaged or missing Fuel Cap seal
- Improper installation of the Fuel Cap
- Damaged Locking tabs on the Fuel Cap and/or filler tube
- Damaged seal points on the Fuel Cap and/or filler tube
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 4

4. INSUFFICIENT VACUUM SUPPLY TO THE EVAP PURGE SOLENOID
Inspect the Evap Purge Solenoid vacuum supply hose for proper routing and installation.
Make sure the vacuum supply hose between the throttle body or intake manifold and the Evap Purge Solenoid is free from any obstructions or blockage.
Make sure the vacuum port at the throttle body or intake manifold is free from any obstructions or blockage.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 5

5. EVAP PURGE HOSE/TUBE OBSTRUCTION
Inspect the Evap Purge hose/tube for proper routing and installation between the Evap Purge Solenoid and the Fuel Tank and between the Fuel Tank and the Evap Purge Canister.
Make sure the hose/tube is not damaged or kinked and is free from any obstructions or blockage.
Were any problems found?

Yes

- Repair or replace as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Go to 6

6. EVAP PURGE SOLENOID
NOTE: After disconnecting the Evap Purge Solenoid vacuum connections, inspect the lines and solenoid for signs of contamination.

Disconnect the purge lines at the Evap Purge Solenoid.
Using a hand vacuum pump, apply 10 in Hg of vacuum to the "CAN" side of the Evap Purge Solenoid.

NOTE: The solenoid should hold vacuum for a minimum of 15 seconds.

Turn the ignition on.
With the scan tool, actuate the Evaporative Purge Valve Solenoid Duty Cycle to the ON position.

NOTE: The vacuum should drop when the solenoid is actuated.

Does the solenoid function as described above?

Yes

- Go to 7

No

- Verify that there is good pin to terminal contact in the Solenoid and the Powertrain Control Module connectors. Replace the Evap Purge Solenoid if no problems were found in the connectors.
- Perform the PCM Verification Test. Powertrain Verification Test

7. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Evap Purge Solenoid and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Switch, Solenoid, and the Powertrain Control Module connectors.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test. Powertrain Verification Test

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test. Powertrain Verification Test