[sambusik]

And if so, was it diagnosed and what was the reason?

Mine came on this morning. I got my 15K service at 14400 and maybe they forgot to reset something. Coz the check engine light went on at 15100.

 

[shabby]

My light came on at 3500 miles and turned off at about 5000, the dealer said something about it might be the gas cap wasn't tight enough? Seemed weird to me that it just decided to turn off one day though?

 

[sambusik]

ok, funny story, took the car in to get the chcek engine looked at. Turned out my girlfriend hadn't tightened the gas cap when she filled up the car last week!

The service guy told me that 90% of the cases where the check engine light is on, is from the gas cap not being tightened fully.

needless to say, I felt like an idiot.

 

[Jeff Andrews]

If the IS300 is anything like a 99+ VW than a loose gas cap will cause the CEL to come on. It has happened to many VW drivers. Make sure it clicks a few times before you stop turning.

 

[JW]

The loose gas cap thing seems to occur for all cars with OBDII.