P0441-EVAP PURGE SYSTEM PERFORMANCE

For a complete wiring diagram Refer to Section 8W.

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 it is less than specified, 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:
With the engine running, after the Evap System small leak test has passed.
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.

Possible Causes

EVAP PURGE SOLENOID VACUUM SUPPLY

EVAP PURGE HOSE/TUBE OBSTRUCTION

EVAP PURGE SOLENOID

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1.VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION

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

Is the DTC Active or Pending at this time?

Yes

Go To 3

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

3.VISUAL INSPECTION

Were any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 4

4.INSUFFICIENT VACUUM SUPPLY TO THE EVAP PURGE SOLENOID

Were any problems found?

Yes

Repair the vacuum supply hose/tube as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go to 5

5.EVAP PURGE HOSE/TUBE OBSTRUCTION

Were any problems found?

Yes

Repair or replace as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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.

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

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

Does the solenoid function as described above?

Yes

Go To 7

Replace the EVAP Purge Solenoid.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Were there any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)