Normal Operation

The PCM monitors the fuel tank evaporative emission system for significant leaks that occur following refueling of the vehicle. Once the PCM detects a fuel vapor leak, the PCM sends the Instrument Panel Cluster (IPC) a message over the High Speed Controller Area Network (HS-CAN) communication bus to turn on the CHECK FUEL FILL INLET message. DTC P0457 sets in the PCM following a successful cruise test, which is initiated when the vehicle is driven at a steady speed above 64 km/h (40 mph) for a duration of approximately 4-5 minutes. If the PCM is unable to successfully run the cruise test, the IPC does not receive the message from the PCM and the CHECK FUEL FILL INLET message remains off.

If the IPC does not receive the fuel cap off data from the PCM for 5 seconds or less, the IPC defaults the CHECK FUEL FILL INLET message to the last setting, based upon the last known good data message. If the IPC does not receive the fuel cap off data from the PCM for more than 5 seconds or if the data received is deemed invalid, the IPC sets DTC U0100:00 in continuous memory and defaults the CHECK FUEL FILL INLET message off.

NOTE: If DTC U0100:00 is set in the IPC, other observable symptoms may be an inoperative speedometer, temperature gauge (except hybrid) or odometer.

DTC P0457 (Evaporative Emission System Leak Detected) (fuel cap loose/off) - sets in the PCM if a fuel tank pressure change greater than -23.7 kPa (-7 in-Hg) of vacuum within 30 seconds after refueling occurs, or there is an excessive purge (fuel vapor) flow of greater than 454 g (1.0 lb) per minute.

This pinpoint test is intended to diagnose the following:

Evaporative emissions concern
PCM
IPC