Audi A4 B6 1.8t Coolant Temperature Sensor Replacement DIY (A4, A6, Golf, Passat, & More)

►The coolant temperature sensor on the Audi/VW 1.8t is known to fail in a variety of ways, both mechanically and electronically. Replacement is straightforward and can be done in your garage or driveway at home with minimal tools.
The coolant temperature sensor is a simple 4-pin thermistor and has two main failure methods. If you've noticed that your coolant temperature reads incredibly low, or that your fans are running constantly, this means that it has failed electronically. Due to the 4-pin design with two going to the ECM and the two going to your instrument cluster, it is possible that your cluster reads that things are working properly, while your ECM reports differently. You should read the output from your ECM to determine if this is the case.
The second failure method is even simpler to diagnose. You will notice a coolant leak coming from the bottom of the sensor at the O-ring with coolant dripping onto the heater hose.
Either failure means that you should replace your Audi's coolant temperature sensor immediately. Cory Calvin, our Motorsport Engineer, walks you through how to replace this sensor on any Audi model with the 1.8t engine.
Read this DIY on our blog: blog.fcpeuro.com/how-to-repla...
Read more Audi DIYs, news, and guides on our blog: blog.fcpeuro.com/tag/audi
Tools required to replace an Audi coolant temperature sensor:
90° Tool Pick
Flat Head Screwdrivers
Inspection Mirror
MAF Cleaner
Coolant Pressure Test Kit
Floor Jack
Jack Stands
Flashlight
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[@thehelpingwrench1845]

I have a 2004 Audi wagon and I can say it is so much easier and less risk to do it from up top and not from transmission but a great video!

[@danoontjeh123]

Thanks for the tip on tilting the engine. My sensor just failed, and I know it was stupidly tight to get stuff behind there when I took the cylinder head off and back on a while ago.

[@angelgomez9339]

I change my without jack the car take couple hose and done the hard part is to put the clip without dropping inside the engine but working in my a4 1.8t b6 I developed a good touching sense to doing things without looking at the spot so for me skip steps sometimes thanks for the video help me good 👍

[@dunloplego]

Very detailed video. I’m not going to do it myself but now I know what’s involved so now my mechanic can’t charge me an arm and a leg for such a simple job

[@ICERAINMusicOfficial]

This is one of the most detailed videos. Thanks. Merci beaucoup.

[@ArtistryAuto]

Love the USP more videos w it

[@rjack151]

I’ve got to honestly say. Worst possible location for the coolant temp sensor. I’m sure that I’m not the only person that has thought that or said it. But I’m so used to MK4’s where it takes longer to open the package that the CTS came in, than it does to actually change it lol. Nice video though 🤙🏻

[@Landaultd]

Really nice, I'll do now in my A6 C5 1.8 20v....

[@teamemusrcreviews3225]

Very nice accurate video👍👍 wish me luck tomorrow🚗🚗🚗

[@NHPhamousPolo]

Doing this right now as we speak, with a 1999 passat 2.8 v6....the sensor is a PITA to access. I thought i had it in correct, went to top off the coolant reservoir and coolant came POURING out the sensor. You just showed me that i did not have it sitting properly and need to push it down more and secure the retainer clip better.....thank you so much for your very detailed and easy to understand explanation, MUCH appreciated

[@blacklotus432]

Thanks a lot

[@wesmurphy2608]

Whats the hose that goes to the silver part and connects the crank case vent valve ?

[@hawberpeshawa2121]

Thanks for this explination ,,, i have Passat 1.8 T ,2004 ,, but i have other problem , the stik who is going to inside sensor , was broken and was not contacted to the stik with 4 cable and diffrent color ( white , red , Gris , black ) the problem i do not know which pin number go to that color ,, please need help to that color exactly to there pin number ( 1, 3 and 2 , 4 ) ,,,,

[@zeph1]

what about the b8??? I've been looking everywhere for a tutorial please help

[@whatsshaken]

Is it ok to tilt the engine on a 3.0 V6?

[@gabrielmoraes6324]

Criando coragem e absorvendo toda a paciência do mundo antes de começar a trocar esse sensor na minha Avant B7. 😢😂

[@gabrielmoraes6324]

Fiz a troca. Meu caso estava vazando pela borracha do sensor quebrada. Não precisei desmontar nada. Levei 2h pra fazer. A parte mais difícil foi encaixar de volta o sensor corretamente.

[@X400DYL]

Is this the same location for a A4 B7 2.ol TDi Temp gauge drops to cold then back up to half way every 10 mins or so

[@MALUMEMALUME-mn9tg]

What if you put a new temperature sensor with same part number but when you start your car it start after many attempts . Bky engine 1.4 vw polo.

[@andrewszekely6547]

I have a 2001 AUDI A4 Quattro Avant 1.8 liter Turbo. Engine code: AWM. About 12 years ago a replaced the coolant temperature sensor because the gauge in the instrument panel displayed cold coolant, although it was hot already. Just this part of the sensor was faulty. There was no error code! Recently I noticed some coolant drops under the sensor! It seems it started leaking. I do not know when it is started leaking. My wife has been complaining for years (!) that she smells coolant when we drive. The oil has been leaking for 20 years, I always thought it was the oil dripping on the exhaust system... There is no error code this time either!! I am about to buy a new 4 pin sensor with a new O-ring and replace it....

[@alimjafari5624]

Hi, Thanks for a great video. I changed the sensor on my audi a6 2008 but sometimes shows the correct temperature sometimes shows nothing. But I haven't had the opportunity to update it with the computer, what can you recommend? Thanks in advance

[@fcpeuro]

Scanning for codes first and clearing them is an easy place to start diagnosing the change in readings!

[@guylipsky3599]

On mine the plug went bad , one wire fell off after pulling the plug off the other fell off I ordered the plug and pigtail this also seems to screw up my AC now I am not sure which wire goes were.

[@manuelquijano146]

Would this work for my 2018 audi s3

[@tatax1991]

Thanks for video, i have a problem I appreciate if you can help me. My audi a6 c5 3.0 model 2002 has a problem that the cooling fans are kicking in late at 108c , I replaced the fan control module, and the coolant temperature sensor, same problem exist, when the gauge pass the middle, and the temperature shows 108c on the scanner, the fan kicks in. I read that the fans should activate at around 92-93c. Is there anything else i should check. Please I need your help. Thanks a lot

[@GlobalDesignHD]

the fans have modulse inside they break often did you replace the fan

[@kspree9649]

I can’t find any help or vids on aux coolant pump I’m not getting power to connector fuse is good p192700 can’t see breaks in wire please help

[@damianbrzeski969]

Do you need to drain water coolant from car before taking the sensor out

[@RonaldoHarapi-up4sq]

Please what value has a normal sensor with 4 pins???

[@lincolnbothang7258]

Hi, thanks for the video. I recently replaced mine on my Polo GTi 1.8t and I have been good gas mileage ever since and fault is cleared from ECU.

[@orgrimdoomhammer2161]

hey man, i need to ask you, i have passat 1.8t and i have lpg instaled too, on ecu i have check engine notification, on diagnostics it saids its lambda sonde, but on lpgs ecu it saids multiple errors conected to temperature sensor, now i noticed thet when i clear ecu code, i have good mpg, untill it cames up again, and start showing grand mgp, i noticed too that temp needle is altering from 0-90. Now my question, can this tiny sensor almost double the fuel consumpion??

[@lincolnbothang7258]

@@orgrimdoomhammer2161 yes, from what I've experienced it causes really terrible gas mileage. From what I researched it is either the CTS or the thermostat that throws off the error. So start by changing the CTS clear the code and observe.

[@orgrimdoomhammer2161]

@@lincolnbothang7258 changed it, bord now showing normal values, itll take time to make some distance and test it out :D error still showing, i need to find some one to delete it from ecu

[@adizillich6648]

Hi Lincoln, I have got a polo gti as well and trying to sort the P0118 code and bad fuel consumption. I will replace the sensor and thermostat as well. Wanted to check if you had to tilt the engine as I don’t think so as the polos are mounted side ways opposed to length ways in the a4 shown in the video. We should have more access, is that right? Thanks mate .

[@lincolnbothang7258]

@@adizillich6648 yes, no need to tilt engine sideways. The sensor is on the right side of the engine and the thermostat on the left below the alternator I think. However, I'm not quite sure on removing the thermostat.

[@fredmann8799]

What did you use to lubricate the O-ring?

[@TheBFBomber]

I think silicone spray.

[@garrettguitar]

Also silicon O-ring grease from Super Lube works great!

[@denisteuca]

where is at audi a7 2015?

[@dertobbe1176]

What are the possible problems with a defective sensor?

[@Tomijee]

Our 2005 a4 didn't start at all when sensor was "broken", started only when pre heated.

[@jazz4life]

Couldn't get mine to seat right for the life of me. This video helped me a lot. I've been trying to press straight down instead of working it in. Gonna try this in a few min. Thanks for always making great vids.

[@jeffdawes9029]

The new one I bought was just little bigger. I tried installing it without the O-ring , the new one, still would not fit. I'll be getting a new one tomorrow.

[@tiko4621]

@@jeffdawes9029 same thing I feel victim to as well, I got an aluminum flange kit and everything worked wonderfully except for the coolant sensor not seating properly in the sensor housing. Had a brand new leak where there wasn’t one before!

[@jeffdawes9029]

so, my second new temp sensor worked.

[@tiko4621]

@@jeffdawes9029 in my case the senspr was not wrong. It was the housing 100%. People that haven’t done this yet, if you went eBay route like I did for these parts, make sure they fit right before doing the install! Otherwise you’ll be ordering another properly fitting piece lol

[@craftyisaac]

im assuming it worked lol

[@kingcory21]

Do you know the lifespan of newer (2015) Audi coolant?

[@fcpeuro]

With any coolant, whether a new formulation on an old one - we recommend you change it every 2-3 years as the coolant also lubricates and will lose some of that lubricity over time which can cause corrosion.

[@stvbisram10]

Thanks for the video, do you guys sell the shirt you are wearing?

[@fcpeuro]

Hi Steve - we don't currently have our team shirts for sale. However, you can shop all our available shirts here: www.fcpeuro.com/products?keywords=fcp%20euro%20shirt

[@BerryMK7]

FCP Euro when are they gonna be available for sale? I want the hoodie version

[@kervincoss5396]

What did you use to lubricate the o-ring?

[@fcpeuro]

Hi Kervin, you can use coolant to lubricate it.

[@RonaldoHarapi-up4sq]

I changed mine and now fan start working at 98 degree. Plus another issue... not work at full speed at 105 degree. I change 3 times and same problem

[@maketzuzu6753]

Might have to do this myself too. Is it located in the exact same spot in B7 Audi A4?

[@DamnWatchThis]

Did you ever figure that out I’m having to replace my sensor now

[@mishka4705]

Same for A4 B7

[@shaydzforlyphe9693]

This is happening to me right now with my 2012 Passat. It causes misfires and car shuts down and because it’s hot, it has to be cooled down to restart.

[@fcpeuro]

then hopefully this makes it an easy fix!

[@sawkpawn4071]

That happened to my 98 a4 B5 1.8t. The idle will bounce the engine check light comes on engine will shake and sometimes shuts off. Won’t turn on right away till engine cools. Replaced coolant sensor and it was back to normal.

[@layziehussle2624]

Hey when I put the C clip back in it doesn’t want I tried so many times it doesn’t want…. What should I do?

[@fcpeuro]

You will want to remove the sensor again and make sure it is seating itself all the way done. Some lubricant on the o-ring never hurts!

[@layziehussle2624]

@@fcpeuro I tried and and two of the C clips are broken now 🤦🏾‍♂️🤦🏾‍♂️🤦🏾‍♂️

[@serhiitkachyk3425]

👍

[@Kiss__Kiss]

Why did you have to do this on a USP?? I miss my '04 USP lol

[@fcpeuro]

Maybe it's a sign that you need another USP :D Appreciate your support Kiss Kiss!

[@Kiss__Kiss]

@@fcpeuro I do love the design, but it's 2020 an I have been going back and forth thinking if an Audi S3(Post facelift), Or another Subaru STI would fit the bill. Although not to get too deep into this chat but, I also miss my 2.7T Leaky but FUN engines. lol PS: And just for fun, I do have to say, I used to buy a lot of parts from you guys about a decade ago for several of my Audis..

[@Toxicdemon2]

Why don't V.A.G. put those sencors on some more conveniant places ???

[@fcpeuro]

We ask ourselves that same question all the time

[@nokuthulalanga5721]

Pickup sense

[@spbub]

Interesting the clip on my 2004 BEX 1.8t was facing forward not towards the bulkhead. Total pig of a job.

[@marioosa]

What were your symptoms that you decided to change it ?

[@spbub]

@@marioosa Fan was coming on with a cold engine and going off once slightly warm. Gauge was reading fine.

[@marioosa]

​@@spbub Thank you 😊 Did you get any missfires on cold starts ?

[@spbub]

@@marioosa Nope, car ran perfectly

[@marioosa]

@@spbub Thanks a lot and all the best to you 🙂

[@prano550]

all that just to change a small sensor ,Germans are loco in Engineering 🤔😂

[@fcpeuro]

You have to think like a German engineer working on German vehicles :) At least it helps.