NGC

P0455-EVAP SYSTEM LARGE LEAK

For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
With the engine running, during a cold start test with the fuel level above 12%, ambient temperature between 4° C and 32° C (39° F and 89° F) and the fuel system in closed loop. The test runs when the small leak test is maturing.

- Set Condition:
The PCM activates the Evap Purge Solenoid to pull the Evap system into a vacuum to close the ESM switch. Once the ESM switch is closed, the PCM turns the Evap Purge solenoid off to seal the Evap system. If the ESM switch reopens before the calibrated amount of time, a large leak error is detected. 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 and record the related Freeze Frame data if any DTC(s) 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: Since a hot vehicle can conceal a leak, it is best to perform this test at room temperature.

NOTE: A loose gas cap could have caused this DTC to set. Make sure gas cap is tight and in good condition. Make sure the gas cap meets OEM specifications.

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.
Is the status Active for this DTC?

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. EVAP PURGE SOLENOID
Disconnect the purge lines at the Evap Purge Solenoid.
Using a hand vacuum pump, apply 10 inHg 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 Evap Purge Solenoid to the ON position.

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

Does the solenoid function as described above?

Yes

- Go to 5

No

- Replace the Evap Purge Solenoid.
- Perform the PCM Verification Test. Powertrain Verification Test

5. EVAP PURGE HOSE/TUBE AND FRESH AIR FILTER OBSTRUCTION
Turn the ignition off.
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 and fresh air filter are not damaged, kinked, and free from any obstructions.
Check for any kink in the purge line connecting the LPV (Linear Purge Valve) to intake manifold.
Were any problems found?

Yes

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

No

- Go to 6

6. CHECKING THE EVAPORATIVE SYSTEM FOR LEAKS
Perform the diagnostic procedure for *CHECKING THE EVAPORATIVE SYSTEM FOR LEAKS. Checking the Evaporative System For Leaks
Were any problems found?

Yes

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

No

- Go to 7

7. EVAP SYSTEM MONITOR SWITCH
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Evap System Monitor Switch 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 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 the Evap System Monitor Switch.
- Perform the PCM Verification Test. Powertrain Verification Test