P0457

P0457-LOOSE FUEL CAP



Theory of Operation

Fuel level is recorded when the ignition key is turned off and is compared to the fuel level when the ignition key is turned back on. The PCM recognizes an increase in fuel level and will fail the Medium leak test because the fuel cap is broken or not installed properly. GAS CAP will be displayed in odometer to inform the owner that the cap is off of loose.

- When Monitored:
With fuel level between 15% and 85%, engine off time greater than 8 hours, engine temperature below 36° C (97° F), engine running for between 2 and 10 seconds, purge valve closed, LDP solenoid supply voltage between 6.0 and 18.0 volts, and vehicle speed below 55 km/h (34 mph). The test can also be started by a request from the service tool.

- Set Condition:
PCM turns the EVAP Purge solenoid off to seal the EVAP system prior to starting the leak test. The PCM activates the LDP Solenoid (on/off) to apply intake manifold vacuum to one side of the Leak Detection Pump to create a pumping action. The LDP pumps up the fuel tank system to a given pressure to test for leaks. If the system has a leak, the LDP pressure switch will then reopen after a leakdown time (the time measured between switch events) the length of which determines the classification of the leak (very small, small, or large). If the vehicle has recently been fuelled, and a large leak is detected, the system will indicate that the fuel cap may not be on correctly. Two trip fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding Pre-Diagnostic Troubleshooting Procedure.
DTC IS ACTIVE

NOTE: If DTC P0455-EVAP SYSTEM LARGE LEAK is set along with this DTC, perform the diagnostic procedure for P0455 before continuing with this test. P0455

NOTE: Do not replace the gas cap for DTC P0457-EVAP SYSTEM - LOOSE FUEL CAP.

1. With a scan tool, select View DTCs.

Is the status Active or Pending for DTC P0455-EVAP SYSTEM LARGE LEAK along with this DTC?

Yes

- Perform the diagnostic procedure for P0455-EVAP SYSTEM LARGE LEAK. P0455

No

- No repair is necessary. Verify that the gas cap is in place and tight. Clear DTCs and follow the directions outlined in the Owners Manual on resetting the odometer or message center display.