coolant temp sensor

[ntrcptr]

where is it located? any write ups on how to replace? I just received the Green one.:mech:

[speedtrapped]

The sensor is located beside the Driver side MAF, actually about 4" over but in that location. The air box has to be removed, car needs to be cool, unplug harness, there is a black C clip holding it in place( be careful, heat makes them brittle, I snapped mine trying to reinstall) pull up on it and it will pop out. Make sure rubber o ring is removed and replace with new one. I had to use a hard rubber block and lightly tapped it into place due to the new o ring, reverse process pretty easy. Getting the C clip back on is tight, unless u have small hands and a 90 degree needle nose.

[Aronis]

and don't tear the vacuum hose going to the diverter valve for the secondary air injection system (my mechanic did that when he replaced my coolant temp sensor two years ago).

[SAF]

Yeah they didn't quite make it IMPOSSIBLE to get at, but they did laugh when they placed it.

[ttboost]

I tied a wire to my C clip so I would NEVER drop it again..works like a charm...

[ntrcptr]

The sensor is located beside the Driver side MAF, actually about 4" over but in that location. The air box has to be removed, car needs to be cool, unplug harness, there is a black C clip holding it in place( be careful, heat makes them brittle, I snapped mine trying to reinstall) pull up on it and it will pop out. Make sure rubber o ring is removed and replace with new one. I had to use a hard rubber block and lightly tapped it into place due to the new o ring, reverse process pretty easy. Getting the C clip back on is tight, unless u have small hands and a 90 degree needle nose.


hmmmm....sensor replaced.... is there another one?

[speedtrapped]

what led you to believe the sensor wasnt working? If your getting code of or running fans, then maybe needs to replaced again, or at least unplug and replug, clear codes....see what comes up

[ntrcptr]

what led you to believe the sensor wasnt working? If your getting code of or running fans, then maybe needs to replaced again, or at least unplug and replug, clear codes....see what comes up

car warms up unusually fast. from cold start...two blocks and temp gauge says/indicates its fully warmed.

[SAF]

Does the gauge stay there at OT? When mine went, the temp needle would go from hot to cold to hot erratically and I had idle speed issues.

[ntrcptr]

Does the gauge stay there at OT? When mine went, the temp needle would go from hot to cold to hot erratically and I had idle speed issues.

nope... none of that...well? no apparent performance issues..( i do have EGT SENSOR code)hmmm...how fast should these car warm up?

[4everRS]

You may have air in the system. Try to bleed it. You may know how, but you'll pull the heater hose to exposethe weep hole and let the car run for 10 or 15 minutes. You'll need towels on hand.

[ntrcptr]

You may have air in the system. Try to bleed it. You may know how, but you'll pull the heater hose to exposethe weep hole and let the car run for 10 or 15 minutes. You'll need towels on hand.

unfortunately your dealing with an armchair mech here..pix would help...(blush)

[4everRS]

nope... none of that...well? no apparent performance issues..( i do have EGT SENSOR code)hmmm...how fast should these car warm up?

yikes, egts usually mean an engine drop. It can be done with a transverse bar and lower the rear of the engine though.

These cars warm up noticably faster that other cars I've had, but definatley not 2 blocks.

[audiprotn]

Sorry for the necro bump.

My question is:
My engine temp goes from this http://i169.photobucket.com/albums/u225/audiprtn/8640A2F4-6EE5-4D73-AFB3-AF01A15C96CD-2012-0000012E6E93EA75.jpg
When I take it really slow
To this http://i169.photobucket.com/albums/u225/audiprtn/82C4B248-192D-4098-B72F-01A8110733EF-2012-0000012E696373FA.jpg
When I go around 75 on highway.

It's really windy and around 35f outside.

Is this normal? Or coolant sensor/thermostat going bad?

[kday]

I wouldn't suspect the sensor for that. It could be the thermostat is starting to stick open a little. The gauge is not linear so who knows how cool you are running. I'd take a look at the coolant temp via VAG-COM to be sure. FWIW when my thermostat was bad it took a long time to warm up, and on the highway the needle dipped to the first tick right of C. I would keep an eye on it and unless it gets worse live with it until your next scheduled timing belt change. You can't replace the thermostat without doing the whole belt service.

[SFJ_RS6]

In my experience with various Audis, it's not unusual for the coolant temp gauge to drop somewhat at highway speeds. I attribute this to the increased air flow thru the radiator. The colder it is, the greater the effect.

[lswing]

Bit cooler only driving 75:)

[audiprotn]

Thanks guys,
drove my buddy's rs6 today, same thing happened to his gauge. So I assume its weather/air flow related.

[JSRS6]

Audiprotn, welcome to the forum. Where are you located?

[audiprotn]

Audiprotn, welcome to the forum. Where are you located?
Thank you, I'm from Chicago

[4everRS]

Thanks guys,
drove my buddy's rs6 today, same thing happened to his gauge. So I assume its weather/air flow related.

I don't think this is right. I live in MN. It gets cold here. I have never experienced this. Even in -25 weather.

http://i864.photobucket.com/albums/ab210/crocodile64/Picture.jpg

I'll bet you at least a nickel that your thermostat is going. And your buddy's.

[audiprotn]

I don't think this is right. I live in MN. It gets cold here. I have never experienced this. Even in -25 weather.

http://i864.photobucket.com/albums/ab210/crocodile64/Picture.jpg

I'll bet you at least a nickel that your thermostat is going. And your buddy's.

Possible, im at 69k miles and he is at 89k.
Replacing my thermostat at 75k miles with timing belt job.

[hahnmgh63]

The Coolant Temp gauge reading is "Smoothed" by the Instrument Clutster/ECU so minor changes in actual Coolant temp don't show on the gauge, only larger changes. If you hookup Vagcom and do some loaded runs up a steep mountain road or coasting down the same mountain road you will find the actual temp reading will fluxuate by by 10'F without any noticeable changes in the gauge. A gauge reading change momentary could be: Temp Sensor, Instrument Cluster, ECU. Most likely in that order. A more constant Hot or Cool reading would most likely be a Thermostat issue. With outside temps in the mid-40's (Farenheit), my car takes about 4~5 miles to show normal temp (after starting and idling first for about 2 to 3 minutes), oil temp isn't warmed up for almost 10 miles.

[kday]

Incidentally I've replaced 5 or 6 thermostats on the 3 Audis I've owned to date. All the same design, all but one from the dealer with the OOOO stamp. I've never replaced a thermostat on any other make of car. Make of that what you will...

[Jimmy Joe]

Thanks friend Hahanmgh, Nothing like knowledgeable advice. You, V8weight and DHall1 among others make this site very special and valuable.

[hahnmgh63]

Now Kday on the other hand I'm on Audi's number 4 & 5 from over the past 25yrs of Audi ownership and only Audi #4, a '01 tt 1.8t 225bhp ever had a Thermostat issue. The tt started to run a little cooler, just my luck it started to do it in late fall of last year and I couldn't take it any longer over last winter so I did a Timing Belt/Waterpump swap on it. Just in time as it turned out as it had one of the cheap waterpumps with the plastic impeller than I could see had cracks starting all the way around the circumference.

[JCviggen]

I'll bet you at least a nickel that your thermostat is going. And your buddy's.

Ditto. I'll bet 2 nickels.

Mine never moves doesn't matter if it's -25 or +30C outside standing still or moving. Once had the temp sensor go bad (when I picked up the car from a timing belt/water pump/thermostat change, go figure) but that gave large unpredictable swings regardless of the speed the car moved at.

Lower on highway and higher in traffic means it's airflow related, which means it's water flow related, which means the thermostat is sticking at a certain level of opening.

[kday]

Now Kday on the other hand I'm on Audi's number 4 & 5 from over the past 25yrs of Audi ownership and only Audi #4, a '01 tt 1.8t 225bhp ever had a Thermostat issue. The tt started to run a little cooler, just my luck it started to do it in late fall of last year and I couldn't take it any longer over last winter so I did a Timing Belt/Waterpump swap on it. Just in time as it turned out as it had one of the cheap waterpumps with the plastic impeller than I could see had cracks starting all the way around the circumference.

Interesting. luck of the draw I guess. I think I need to do the 'stat in my A6 again soon. either that or the gauge/sender is off. At least on the V6 it is relatively easy. I had to do the timing belt job early on my RS6 because the thermostat was sticking open and causing an ECU fault code.

[Dmb408]

Audiprotn was this the ECT or the thermostat? I'm having the exact same issues.

[lswing]

I don't think this is right. I live in MN. It gets cold here. I have never experienced this. Even in -25 weather.

http://i864.photobucket.com/albums/ab210/crocodile64/Picture.jpg

I'll bet you at least a nickel that your thermostat is going. And your buddy's.

17.7 average? New world record! You must get plenty of highway cruising...

[4everRS]

17.7 average? New world record! You must get plenty of highway cruising...
Ha. I must have. This is a pretty old thread. That was my Daytona car.