Test U: The Check Fuel Cap Warning Indicator Is Never/Always on

PINPOINT TEST U: THE CHECK FUEL CAP WARNING INDICATOR IS NEVER/ALWAYS ON

U1-U4:

Normal Operation
The powertrain control module (PCM) monitors the fuel tank evaporative emission system for significant leaks that occur following refueling of the vehicle. 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 27g (.06 lb) per minute, the PCM sends a message to the instrument cluster over the communication network to illuminate the check fuel cap warning indicator.

Possible Causes
- PCM
- instrument cluster