Mileage issues, coolant temp sensor CEL finally came on

[onlyaudis]

we did Revo stage 1 on my Wife's TT last Fall, and the car never ran better. mileage dropped to terrible number though a few weeks later, with no codes. i replaced the MAF and O2 sensor. no change in mileage. Finally, a CEL came on, and we found a coolant temp sensor code. which is what I was thinking it might be. Wasn't leaking or anything, the sensor was just tired. We put a new sensor in there, and not only did the mileage go back to where it was (FWD TT TIP car, 22 city, 30 HWY) but the thing will light the tires up when you get on it now. That is a very important little sensor on these cars.

[ArTTemis]

Thats good to know I'll have to do the same!!!!

[ECS Tuning-Audi]

Indeed, these little buggers do work in conjunction with your MAF and O2 sensors to adjust your fuel trims. When they start going bad they rarely trigger a CEL but will destroy your fuel trims. Nice work and nice post OP.

[Mantvis]

Thats good to know I'll have to do the same!!!!

when you do it, tell us if it improved!!