Why might the check engine light on a 1998 Toyota Camry come on and then go off when you fill the gas tank and come on again when tank is approximately half full?

Answer 1

i have a 1999 Camry and basicly the same thing is happening. i took it to a service dealer and i was told it was from over filling the gas tank. gas runs down the vent line and screws up a sensor in there of some kind i was told it doesnt affect the operation of the vehicle at all. it is around 190.00 to fix the problem so for now i have decided to live with it

AnswerMy "check engine light" went on and off intermittently (no pattern). The manual's first answer is that the gas cap may not be on tight enough, or is faulty, a common problem. A shop with a diagnostic machine can check this. Unfortunately, had to go to the manual's second answer, "see your dealer". My shop's scanner said I had a "faulty oxygen sensor", a much more serious problem, but not an emergency (yet). Gave me technical info on a recall for this part, up to 96 months or 80,000 miles. Answer(another 1999 Camry owner)Today, my check engine light went on immediately after filling my gasoline tank. It stayed on even after driving another 30 miles, with several turning off the engine and re-starting. Thank goodness for the answer above about the over-filled gas tank. After reading this, I simply disconnected my battery for a few minutes to reset the light. After re-connecting the battery, the light was no longer on. I figure the excess gas has evaporated from the vent line. This site saved me $$$$$, and wasting time at the dealer. P.S. I had read a dozen other sites about check engine lights in Camrys, but no other site brought up the situation of the gas tank over-fill. Thank you.