How to Replace a Temperature Sensor MKIV VW/Audi, Jetta, Golf, 1.8T DIY


Fix Temp Sensor DIY

Recently my temperature sensor had gone out on me again, so I figure this time around I'll take some pictures and save everyone a couple hundred dollars from the dealership. Most of the original sensors placed in the MKIV cars were faulty and instead of a recall VW/Audi was nice enough to come out with a new revised part and let us pay for it. The revised part number is 059-919-501A and will have a green top as opposed to the original black or blue top that was in your car. No matter if you drive the A4, Jetta, Passat, Beetle or GTI this should be the correct replacement part, but always check with your local V-dub dealership. For some reason all the dealerships are charging a different amount for this part so expect to pay anywhere from $25-$40 for this fix. The part can also be bought at Autozone for $8.99 (part # SU5404), I have heard mixed results with using the autozone part but it does come with a two year warranty. Another option is to buy online to save some cash. I don't trust most online stores but one good one for OEM parts is ECS Tuning. Along with the sensor I would recommend buying a new O-ring and clip.

Once the bad sensor is replaced you should see an increase in gas mileage and it is also known to steady the idle as well as making your in dash gauge work properly again. And as always lets give the stealership a call and see how much they charge to do this 10 minute repair. The dealership quoted a price of $161+tax for the repair, parts being about $38. So savings on this DIY is about $120.

Symptoms of a Faulty Sensor

Some cars will receive a check engine light when the sensor goes bad and some will not. If you have an error code go down to your local auto store and have them scan it for free. If you are receiving any of these codes it is most likely your temp sensor.

Fault Codes:

  • 17704 Error in mapped cooling system
  • 01039 ECT Sensor
  • p1296 35-00
  • p0118
  • 16502

Most of the time you will be able to tell that you have a bad sensor by the way your temperature gauge needle randomly floats around or stays at zero or a fourth of the way up when your car is fully warmed up. When my sensor first went out the needle on the temperature gauge just stuck on zero. I took the sensor out gave it a good scrub and it lasted about another half a year (don't be cheap like me, just buy a new one), but both times I did not receive a check engine light so I'm guessing that's just random.

If your temperature gauge is reading above 190 degrees more than likely it is not your temperature sensor but your thermostat or even worse your water pump. Ouch! that's gonna cost some money!

Tools & Part Numbers For the Job

This is a very easy fix only needing a flathead screwdriver and about twenty minutes of time.

  • Sensor: 059-919-501-A or Autozone Part #SU5404
  • O-Ring: N90-316-802
  • Clip: 032-121-142
  • A few sizes of flat head screwdrivers


Coolant in your car after it has been running is extremely hot. So if you do not want to risk a 200 degree fahrenheit money shot right to your face then do not attempt to change this sensor until your car is completely cooled down.

I recommend the "better safe than sorry" method on this one and let your car cool down overnight, then do the repair in the morning. Seeing how the repair will only take most people about ten minutes (thirty at the very longest) this could even be done before you go to work. Another benefit of waiting till the car is bone cold is it will leak very little coolant while swapping out the sensor. If you want to attempt this DIY while your car is still hot use google to find instructions for that method and print yourself out the directions to your local burn victims unit just in case.

The sensor is located in this general area
The sensor is located in this general area
Step 4
Step 4
Step 5
Step 5

Lets Get This Party Started!

  1. Make sure your car is completely cooled down.
  2. Loosen your coolant reservoir cap to release any built up pressure, then tighten the cap back up. By doing this you create a vacuum seal so when you pull out the bad sensor very little to no coolant will leak out while you are making the swap.
  3. The temperature sensor is located directly to the right of your valve cover as you can see in the picture. If you have an Audi A4 or passat it is located between the firewall and valve cover in front of the battery enclosure. You can choose to remove your engine cover if you'd like but you should have enough room with out removing it. I can't say for sure because I have no idea what happened to my engine cover. To remove the cover push down on the screws and twist left (looking at it should be pretty self explanatory).
  4. Once you locate the sensor wedge your flathead screwdriver between the clip and your sensor. If you didn't want to go all out and buy the new 65 cent clip then be gentle so you don't warp or break it. Now pull out the sensor while it is still connected to the wire harness. Some coolant may leak out, if you are concerned you can place some paper towels under the hose before you remove the sensor.
  5. Release the wire harness by using your fingers or a small screwdriver. I talked about these little clips before in one of my other DIY's. Just use gentle pressure, no need to show off for the ladies and get all he-man here. The clips can be fragile so the last thing you want to do is break it. Update: I just broke one off, Here is a diy on how to replace broken harness connectors if you accidently break yours. 
  6. Once your old sensor is released from the wire harness check to see if the o-ring is on it, If the o-ring is not on the sensor then dig it out of the hole with your little pinky finger. (Wow that brings back high school memories).
  7. Before you stick the new sensor in I like to lube up the new o-ring with a little coolant to help it all seal up properly.
  8. Slide your clip in gently, plug the wire harness back in and start up the car. As long as nothing is leaking out then you're good to go. If your coolant is low pour a little distilled water in the reservoir to top it off (do NOT mix it with store bought coolant).

If you do have a check engine light on you have two options now. You can unplug the negative terminal on your car battery for a few seconds which will reset your fault codes or can can just ignore the light for about sixty miles and as long as that was the only problem the light will turn off on its own.

Questions and comments: If you have any please feel free to leave them below.

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Comments 34 comments

dougmed21 5 years ago

I have been reading ur hubs and find them very useful. I have a 2001 1.8 wulfsburg. I was wondering if you have any performance gadgets that you would recommend for this engine / car. Thanks...

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Writen4u 5 years ago Author

Hey Doug,

I'm glad these DIY's help. The 2001 Wolfsburg was my first vw I owned and after a few fixes at the dealership for astronomical sums of money it was the inspiration to write these DIYs! I think it is such a scam that the dealerships can charge over 300 dollars for so many 10 minute fixes. (Sorry a little rant).

As for performance there are quite a few smaller cost mods that are easy to do on 1.8t engines. A short ram cold air intake or just a drop in K&N air filter will help it breath better, a metal diverter valve should help hold boost a little better than the cheap plastic vw one, you can also route the diverter valve to open and close from the intake manifold so the ECU no longer has control of it. I would recommend a chip for the car, it makes a day and night difference. There are all kinds of cheap mods out there, maybe my next article will be about that.

Thanks for the comment.

dougmed21 5 years ago

I would be very interested in seeing your next hub on performance mods. I have a K&N drop in filter. I really don't have power complaint so I don't want to over-do-it. Have you had any reliability issues since you have done these mods? FYI I have worked many years for dealerships such Cummins and caterpillar,and I am well aware how they work. DIY is the only real defence...

Thanks for the reply...

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Writen4u 5 years ago Author

I have done a lot of little mods to my gti. In five years I have not had a problem with any of them so far. I've re-routed air hoses, removed the vacuum box and some other valves, instead of a diverter valve I have a 50/50 blow off valve and I have not yet had a problem with any of it.

I think a lot off it is trial and error depending on your car. Some people can put on a big downpipe and not get an engine code error from the o2 sensors, where as other people end up having to put in spacers.

I hope that helps a little. I recommend just reading everything about whatever mod you're thinking about doing before you do it so you can read the pro's and cons from other people then you can decide if the risk (if any) is worth the reward.

JE 5 years ago

My engine light is currently on, and the code is P1296. Just read through your directions, and am going to try this DIY fix. I'm hoping it works and that it is not something more serious! Fingers crossed.

SubZero 5 years ago

Hi. First off, thank you for very good DIY's. Good pictures and good language is very helpful, and you got plenty of both!

I own a A3 1.8t AUM, and recently the temp gauge in the dashboard has started to show increasing temperature too soon. That is, if I start the car cold (in my area, cold can mean -20 C) and let the car idle for maybe only 2-3 minutes, the needle will start to move. At the same time, the AC will start to increase the fan speed to heat up the inside of the car, even though there is nothing but ice cold air coming out so soon after car was started.

Could these symptoms also be because of a defective temp sensor you think? Or some other more dramatic error? I've been hunting the dreaded 17705 'pressure drop between turbo and throttle valve' for a while now, but that's another story. I guess it's unlikely it's related to the weird temp measures that only started to happen maybe 2 weeks ago.

Greetings from Norway.

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Writen4u 5 years ago Author

Hi sub,

Sorry but i'm not sure what your problem is. AC is meant to pump out cold air, not warm air. So if you have the AC button on you will be getting cold air inside your car.

With your ac on while your car is warming up I figure it's using more gas to run the AC and warming the engine faster. If your needle is fluctuating back and forth then it is surely a bad temp sensor, if it is just rising faster then it is probably because you have the ac on while warming your car in freezing weather. Turn off your ac button and use the heater!

As for your pressure problem, first make sure your diverter valve (DV) has not failed. That is more than likely your problem if you still are running on the original stock one. If that is not the problem try looking for boost and vacuum leaks throughout your hoses.

I hope that helps.

SubZero 5 years ago

Sorry for the language confusion. Normally when I start the car, the temp on the climate control is set to 20 C. It will typically take at least 5 minutes driving until the engine is getting warmer and the fans spin up to heat the inside of the car. It will take just as long before I see the temp needle start to move towards warmer position. That is, until recently. Now the needle starts to move maybe just a minute after starting the car and the climate control will increase fan speed although the engine is still freezing cold. Sometimes I can see the needle drop after it has hit the 90 C mark.

Anyways, reading your DIY it seems very simple to change the sensor, and it's cheap, so I will do it just to see if it makes a difference.

I'm not going to go off topic by talking about the 17705! :) Though I can mention that I've got new aftermarket DV, new N75, new MAF, new coilpacks (free from Audi, yay), new plugs, and also some new pipes and one-way valves in the PCV. I think I'll have someone help me pressure test next.

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Writen4u 5 years ago Author


Ok I understand what you mean. If the car is not overheating and the gauge is going up quicker the temp sensor could be the problem, but I have no idea. Also I read something about the thermostat sticking for people that live in freezing weather (a harder fix) so you might want to read up on that and see it it is matching your problems. Like you said the temp sensor is cheap and easy so it can't hurt to try that first.

Was your car throwing the code before you put on the new DV and N75? if not make sure the dv is in the right direction and everything is tight. It sounds like you have replaced anything that could of gone faulty. A easy way to do the pressure check if you have an air compressor is buy a tire valve ($2) and stick it in to the bottom of an open and cleaned can (like the kind veggies come in) then shove it in to the inlet hose where your maf goes it fits perfect. Run about 8-10 psi (don't over due it) and you will be able to hear any leaks you may have.

SubZero 5 years ago

The 17705 problems started when the car got a new chip (flashed to be precise). That is, I don't know if the code had been thrown beforehand, but I never felt the car hesitate on lower revs then as it does now. I guess maybe I had a leak somewhere before chipping, and that the higher boost pressure post-chip increased the leakage (and thus the problems). I have not tried to revert back to the original program, but I have no reason to believe the new one is faulty. Anyways, I switched out the named parts over time after this, but the fault code gets thrown almost as soon as I clear it in vag-com.

Thank's for the can trick tip. I have in fact seen pictures where someone uses this technique. If the cans have the same diameter in my country, I guess I should give it a go. No air compressor though, so not sure how to solve that. I think I read somewhere that people have been using a bicycle pump with a pressure gauge attached! Poor man's equipment.. :)

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Writen4u 5 years ago Author

Hi Sub,

I'm not sure if you found or fixed your problem yet but I just read about another person having this code and it turned out to be the breather elbow hose coming out of the oil housing. So it wouldn't hurt to check under your intake manifold and see if any of the breather hoses are damaged or if you have a faulty pcv (bleeder) valve. Also check the upper "y" breather hose that has been known to tear over time.

Sam 4 years ago

Have been getting the P1296 issue with my '02 Golf GLS 2.0. I purchased the car last winter (Chicago) used from a dealer. Code came on quick, however as it warmed up the CEL went off. All of umber no problem, car didn't seem over overheat or anything.

Now we're getting back into winter and the p1296 code is returning - somewhat often! My temp gauge on the dash takes an GE to get to the middle - if it even does at all. Heavy traffic (slow traffic) helps warm up the car,however ar highway speeds the needle will move backwards towards low. Obviously when that happens the heat no longer works - not ideal for the mid west!

Replaced the temp sensor (it was already a green one) but code returned on test drive. Could it be the thermostat needs replacing?

I called a VW mechanic who wanted to charge $180 to replace the thermostat...but he also said it could be the water pump that needs replacing - what do you think?

If the water pump was bad, wouldn't it be causing the car to over heat as opposed to stay cool or underwear the engine? Is a water pump an easy job for a DIY'er - if not, what would be likely cost? If the water pump was bad, wouldn't I have faced problems in the summer we've just had?

Appreciate your expertise!

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Writen4u 4 years ago Author


I'd think replacing the thermostat is a good cheap place to start (I think they're around $20). It does sound like that could be causing the problem and I think your right about the water pump, when mine went out it made the car over heat. The water pump is usually done when you do the timing belt which I wouldn't recommend on trying yourself, if you mess up the timing you could be buying a new engine. Cost for timing and water pump job will be around 600-1000.

As for the thermostat I'm sure that is a job you could get done on your own. I'm not to familiar with the 2.0 but on the 1.8t it is not that hard of a job, it was just a pain to get to. I'd start there and hopefully it is just a $20 fix.

jose 4 years ago

Heyy man my 2002 jetta takes like 15-20 minutes just to hit 190 and i can drive it with out hitting the 190 mark because it wont shift any ideas on what my problem might be

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Writen4u 4 years ago Author

I don't know why it wont shift, but it taking so long to get up to temp could be a thermostat problem.

My car now is taking a while to get up to temp to, I'm going to get around to changing the thermostat sooner or later and I'll throw up a DIY.

Josh g Perth wa 4 years ago

Omg I just changed my temp sensor in about 5mins now my car runs car has been over reving or under reving and stalling for weeks mainly at traffic lights in rush hour which is not nice.the garage charged me $80 to tell me I need a new oxy sensor and temp sensor.the temp sensor would have been $70 and the oxy sensor $250 plus around $200 to fit.I bought a temp sensor first from e.bay with a 2 year warranty for $3 plus $7.95 postage to oz from England.I don't think I even need the oxy sensor now I just saved over $500 and the embarisment at the lights every day.Thanks for your help

louie 4 years ago

your good man

Tim 4 years ago

Thanks so much for this! I changed mine out today, gauges work again. I'd be lost without this article...

Raul 4 years ago

Hello guys can any one help me telling me if this are the same step to follow to change the temp sensor on my VW 2002 jetta 2.0 ?

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Writen4u 4 years ago Author

Raul, My wife just got a 2.0l jetta and it is pretty much in the same spot. So the steps are the same but probably a different part number.

martin 4 years ago

thanks i just this on my car. thought it might stop the engine reving by it self.will have to run the diagnostic on it again to see if the 1039 error is gone.

1 thing to add to the tutorial. The coolant stated to flow out when i removed the sensor. i had followed the instructions. just let people know if they do not drain some of the coolant that it will start flowing out like a hose. thanks again

jetta 4 exclusive 3 years ago

help here if i changed then coolant sensor and still does the same thing going up and down and did not change the thermostat. Do i have to changed it?

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Writen4u 3 years ago Author

Yes, I would think changing the thermostat would be the next step. Are you sure that the sensor was good that you used?

TT Driver 3 years ago

Changed the ECT in my '05 TT, but CEL still on. Drove it for 100+ miles and still no change. Thoughts?

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Writen4u 3 years ago Author

One thought is scan it with vag-com and post the results. Nobody can tell you what to fix if they don't know what's wrong. Good luck.

mokete 2 years ago

Hi, I just replace the tempereture sensor,but stil my car stil overheat when I'm driving faster,I'm dring Golf 5 GTI 2008 model,BWA engine,I buy one in VW shop, and the fan's run non-stop,most when I just park the car,fan's run's ±5 -10 minutes,Please help me,Thnx


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Writen4u 2 years ago Author


If your car is overheating and the fans are working I would try changing the thermostat first, as they rarely fail it could be stuck shut. While you're in there, put your fingers in the whole and see if you can feel if the impeller on the water pump is broken. They are prone to failure. Sorry to be the bearer of bad news but more than likely it's your water pump and if it is, make sure you change out your timing belt and tensioner while your in there.

gti zim 2 years ago

Please help i changed my fan switch but my car is over heating iv even connected the fans direct please help

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Writen4u 2 years ago Author

If your fans are definitely working (you can check by turning on your A/C). More than likely either your thermostat is stuck or your waterpump has gone bad and as thermostats hardly go bad it is probably your waterpump if you haven't changed it out yet. The temperature sensor will not cause the car to overheat.

javier 2 years ago

can someone tell me where is the air charge temperature sensor (IAT) in a 99 jetta???i cant find it so i can fix my car.. thanks

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Writen4u 2 years ago Author

If it is a 1.8t it is plugged into the throttle body and hooked on with a 5mm allenhead bolt.

Patpat 11 months ago

What model of VW is in your pictures?

I have a 2003 Jetta 1.8t and was wondering if it would be in the same spot as your pictures show.

I got the P0118 code and suspected it was the coolant temp sensor before even trying to do a scan.

My start idle would be around 1100 RPM then after switching into reverse it would drop to 900 RPM and stay at the idle.

Sometimes it would run a little rough when accelerating from a full stop.

Also my temp sensor would stay pretty much all the way to the left until around 4-5 minutes of driving then finally shoot up to 190F.

And what really tipped me off was how horrible my MPG was.

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Writen4u 11 months ago Author

That car was a 2003 GTI, so yes it will be in the same spot for all MK4 1.8t Jetta's, Golf's and GTI's. On the Audi's and Passat's the engine it turned 90 ninety degrees so it would be near the firewall. Thanks.

Oystein 6 months ago

Tanks for good description..

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