Lexus reported that some 2005-09 GX470 SUVs may turn on the Check Engine light and log one or more of the following EVAP system trouble codes in PCM memory: P0441, P0455 and P0456. One likely cause for the trouble is a defect in the sealing surface of the gas tank cap. Installing a new-design gas cap, part No. 77300-47010, should eliminate further trouble.
To make a definitive diagnosis, clear the stored code(s), then run an Automatic EVAP System Check with a scanner. If any of the codes reset, make sure the gas cap tightens correctly at the filler neck. If it does, this information doesn't apply; continue troubleshooting until the cause of the EVAP leak is resolved. If the cap doesn't fully seat or feels like it's jamming when tightened, install the updated gas cap with confidence.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected]crain.com.