I know during the winter then mpg is lower. But mine only gets close to 19 on a highway. I'd like to find out if the reason might be:

1. my temp sensor is out (cooler temp gauge always shows zero). Is this the reason for higher rpm (around 800 while idling) maybe the engine is trying to "get warmer"?
2. If temp sensor is not the reason then why is rpm higher than normal?
It's 2001 1.8T Quattro stock.
I'm concerned about that because just got this A4 and am compring it with 626 mazda's 500 rpm while idling.
Thanks for your thoughts!

 

Yes if the coolant temp is showing 0 then that sensor will affect the RPM, does the car show any fault codes? As that should be there is the sensor is knackered.

 

the sensor is fairly cheap. u can go down to VW and get a green top for like 25$ or so.

but yea the ects will affect your rpms. ive unplugged mine before when it was bad and my idle was really high. its not a really good idea to drive with it out. you should get it replaced.

 

I have 900rpm idle when engine is warm. 1300rpm when engine is cold. A4 B5 1.6 '98.
It's a bit unsteady idle though.. Maybe I have a problem, and not you.

 

There is no CEL on. Sometimes the gauge would show temp for a second and then drop dead again. I suspect there is bad wire connection somewhere. Will try to find it when it gets warmer because except this and rpm, everything else is working fine.

 

new sensor replacement is a 5 min job, after you identify it.

 

I have the same poblem it is the connection or the ECT sensor itself when they go bad they default to -40 which causes the PCM to think the engine is cold all the time therfore you get high RPM and really shitty gas milage I get about 17 in my 98 2.8Q