I recently got my hands on a 99 FRC. About two months after receiving it I got a check engine light. When I pulled codes I had the infamous P0113 and P1111 codes - relating to the IAT sensor voltage. From what I read the culprit is typically either the harness connector to the IAT or the IAT itself. Obviously neither one of these fixes are difficult or expensive, but it just seemed strange to me they would fail - especially the IAT itself. The car has a Blackwing intake on it and I know that a lot of people tend to over oil these filter elements out of fear of not capturing enough of the dirt. So, for ***** and giggles I pulled the intake out (from the filter itself to the TB) and cleaned the IAT and MAF with MAF Sensor Cleaner, then threw it back together and cleared the codes. The first time I reset the codes the CE light was back on in a matter of minutes. Since cleaning the IAT I have driven the car over 50 miles and haven't seen the CE light and have no stored codes.

In my searches on this forum I never saw this mentioned as a potential fix, so I thought I would put it out there as a thought for those of you getting these codes....if you have an aftermarket filter that requires oiling, it may be your culprit.

Hope it helps.

Kurt