this may not apply to everyone but my check engine light was on and our mechanic ran a diagnostic and told us it had something to do with our fuel pressure, i think... well whatever it was it wasn't a major problem so we weren't gonna drop the $250 bucks to fix it right then.

Then a few days later im fiddling around in the trunk and on the back left corner under the carpet in the well I found a tube. that tube runs from the gas tank to prevent overflows while pumping and whatnot. the tube had been unplugged somehow, probably by somebody throwing the jack in the well. because it was unplugged water had been coming up into the trunk and the tube had fell into the water, hense the check engine light. on lexus and toyota cars, the check engine light is so sensitive it will come on for just about anything.

we plugged the tube back in, reset the battery, and the light went off and its been off ever since. so if your check engine lights on you might wanna check your trunk, it just might save you some cash.