I have a 99 Lex gs300 and the check engine light is on. Just came on one day while driving. Nothing else major is happening with the car, but didn't pass emissions testing at DMV..what could this be?
Check engine light on 1999 Lexus GS300
If your gas cap is tight and you dont have a hose off the evap purge valve from a quick lube checking your air filter then it is most likely a bad air fuel ratio sensor,These are common on these cars.But you do need to have the code pulled with a scan tool.
there are over 1500 possible codes. you need a shop to do a real diag, not a free code pull to determine the issue and give you a bid.