View Full Version : Changed ECT and still have erratic gauge reading

01-15-2010, 07:11 AM
Hi - I recently bought a 99.5 A4 with a coolant temp gauge which would rarely display any temperature. I did some reading and all signs pointed to the ECT sensor which I changed this morning. Since changing, I'm getting more activity on the gauge, but it's still not warming up to 90 degrees and it seems to cool down pretty quickly while driving. I'm trying to figure out what to check next. Should I look into changing the thermostat or could it be that my new sensor is faulty? I'm a bit of a novice at this sort of thing, but I'm not afraid of getting my hands dirty.

Thanks for any help and advice!

01-15-2010, 07:22 AM
I'm having same problems. I've replaced my CTS as well and it takes forever to get to 90 and at other times it's quicker but not as quick as it should be so i'm replacing the thermostat+coolant today. When was yours last replaced? I will let you know how it goes.

01-15-2010, 08:42 AM
yes replace the thermostat and coolant. Sucks to do on an AEB. Might as well do a whole timing belt kit while you are in there.

01-15-2010, 10:44 AM
definitely the thermostat

01-15-2010, 12:36 PM
I just did mine and all is back to normal so i suggest you replace yours as well since you've already done the CTS, it's most likely the thermostat.

01-15-2010, 03:15 PM
Thanks everyone. I just bought the car, so I've no idea when the coolant was last changed. I'll buy a thermostat and coolant tomorrow. Fingers crossed!

01-15-2010, 03:17 PM
yes replace the thermostat and coolant. Sucks to do on an AEB. Might as well do a whole timing belt kit while you are in there.

Is the timing belt something which I can do myself? I don't know when it was last changed, so I was going to take it in somewhere to get it done, but if it's a viable project then perhaps I can give it a shot...

01-15-2010, 04:53 PM
If it's something you've never done before then i wouldn't tackle it on my own. I did mine but with the help of a friend who's done them on other 1.8t motors before. Now i know enough to do it again myself. It all depends on how mechanically inclined you are. There's good DIY on audi world. Just have to make sure the cams and crankshaft don't move. The rest is just a bit of tedious work of remembering/tagging what bolts came out of where.

01-15-2010, 04:54 PM
Too bad i'm not in england right now or i would have come out to glasgow to give you a hand. I go to london quiet often and my wife's from there and has lots of family there.

01-15-2010, 05:40 PM
I'd have gladly bought you a flight up to help! (Probably cheaper than getting a mechanic to do the timing belt.)

I think I might just take the car in to get the belt done. The last thing I want to do is mess that up. I think I'm going to tackle the thermostat this weekend though. Thanks so much for your help - I really appreciate it. If you ever make it to Glasgow I owe you a pint!

01-15-2010, 06:55 PM
This was the scene on my driveway when i did all my belts+waterpump+thermostat.


01-16-2010, 03:46 AM
okay - i'm in over my head!

01-16-2010, 04:10 AM
Just to give you an overview of what the timing belt job entails: http://www.audiworld.com/tech/eng35.shtml