Well I installed a colder running thermostate drove it probably 500-600 miles with 5 passes dont the track. Just cruising along today my "Tuner light" came on went had it scanned, it said that it was runing cooler then supose to? Why would a check egine light come on for that....
thanks nick

 

Because it's running too cold.

It's likely that your car is not able to get up to proper operating temperature. Lot's of people have experienced this!

 

The car wants to get in a closed loop situation with the 02 sensor, emmisions and proper a/f monitoring; hence the car wants to be above a lower temperature threshold with the coolant....i havent really looked into a flash that takes into account a lower temp thermostat....like hypertech for the V8's. Unless your traking your car or live in the desert or subtropical...stock stat is the best option.....imo

 

which code was it?