I own a 2001 I30 with about 59,000 miles. Since I bought the car 18 months ago the service engine light has been on. About a month ago a shop scanned it and said nothing was wrong, they also reset the light. A week later the light came back on. I went to a different mechanic and he connected a small "Mac" scanner and it came back as if nothing was wrong. Again it was reset. A day later it came back on the the mechanic agained connected him scanner. This time it said 1126 undefined? He again reset it. I see here the codes means "P1126 - (2000-2001) Thermostat Function". But what does that mean? The car runs fine other than it seems kinda loud to me and hesitates when I punch it. I had a 1998 I 30 before thisone and it was a lot faster. An ideas, all I want to do is sell the car? Not for this it is just time to get mama a newer car. LOL, Thanks from monterry mexico

It means the engine is not heating up enough to open the thermostat. This could be due to a leak in that area, a faulty themostat or a faulty coolant temp sensor.

Thanks alot for the quick reply

the car doesnt not seem to hot. the temp gauge is always in the middle I believe. I'll get with the mechanic today and see which of those two it most likey could be. thanks