My balt is sending a "Please Check Gas Cap" message every time the tank drops below 3/8's a tank, and then the check engine light comes on the next time I start her up. I've connected a computer and the code shown is 455. Gas cap seems tight, and I double check to make sure. Reset the thing, and today, for the third time, check gas cap message and engine light comes on below 3/8's a tank.

Any ideas? Also going to call the local stealership's service dept, and see what they have to say. Should this be covered under warranty? The car only has 25.1k miles on it and is an 07.

j

 

Standard problem if you still have a warranty go to the dealer, mine is in as of today for a similar issue had P0455 and P0496 in succession.

 

p0455 is an evap leak code.......usually a loose gas cap, but could be anything really in the evap system leaking and not allowing it to hold a vacuum. Have em check it out.

 

DTC P0455
System Description
The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge solenoid valve OPEN and the EVAP vent solenoid valve CLOSED . This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge solenoid valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.

direct from GM