(P2181) Coolant Sensor Replacement - 2003 Passat Wagon 1.8T AWM
NEWS
 
+ Reply to Thread
Results 1 to 16 of 16
Like Tree1Likes
  • 1 Post By scotts13

Thread: (P2181) Coolant Sensor Replacement - 2003 Passat Wagon 1.8T AWM

  1. #1
    Neutral
    Join Date
    Dec 2008
    Location
    Westchester, N.Y.
    Posts
    85

    (P2181) Coolant Sensor Replacement - 2003 Passat Wagon 1.8T AWM

    Hi all,

    I own a 2003 Passat Wagon with a 1.8T AWM type engine. Here is my story on code P2181 and replacing the coolant sensor. I don't know that this solves P2181, but it is what I have done so far. This is going to be a long post so I ask if you're going to quote it please crop what you are going to specifically quote and not quote this entire post. Thank you.


    A while ago my check engine light came on and when I checked with my reader it had code P2181. I googled the code and found that most people on forums suggested replacing one of several coolant related things -- most often the coolant sensor -- to rid of that code.

    Eventually I found this insight on newbeetle.org from a VW tech:
    Quote Originally Posted by agental@http://newbeetle.org/forums/2-0-liter-gas/5464-recurring-code-p2181-cooling-system-performance-2.html
    basically P2181 means the ECM didnt see the engine warm up fast enough or it warmed up TOO fast(water pump impeller is jacked). When a car comes to me with this problem I automatically replace the water pump, thermostat, and ECT. I've done this repair and all 3 peices look to be in good working order so dont assume you can inspect the parts and see which one is broken. I wouldnt trust aftermarket parts either(except for the water pump, plastic impeller sucks). Never had one come back for this.
    Over the last few months I erased the code continually. Each time it eventually would reappear (and oddly enough sometimes disappear) on its own. A little more research and I found out that it would probably be worthwhile to check the freeze frame data to help isolate the problem part. Unfortunately I don't have a reader that can retrieve freeze frame data (I have a CodeKey). And so I decided to replace the cheapest (and what I thought to be the easiest!) part first, the coolant sensor.

    I had previously replaced the coolant sensor on a Hyundai and I've found VW was different because from what I'd read VW's coolant sensor is also a coolant sender. The Hyundai I worked on had a coolant sensor (to signal to the computer to turn the fans on) and a separate coolant sender (to signal to the dashboard gauge the temperature). VW's coolant sensor/sender is essentially a dual element in one unit and either element can fail independently of the other. This is explained in a VWvortex post, but unfortunately their archived site data is offline as of June 8 2010.

    I went to VW dealership and bought a coolant sensor and an O-ring. I gave them my VIN rather than part numbers to get the right parts. Looking back it was a huge mistake was not buying a few (or even one) of the cheap coolant sensor retaining clips. I did not realize how hard it would be to remove the retaining clip without breaking or losing it.

    I found a great thread here that describes in detail with pics how to change the coolant sensor:
    Coolant sensor replacement on 1.8T AWM - with pics - Passat World Forums
    I followed the instructions in that thread and but it was very hard for me and I could not do it exactly as instructed. I should note I did not take the heatshield off. It didn't seem to be a problem. I should also note I have skinny arms and hands. If my arms or fingers were even a little bit thicker I don't know if I could have done it in any way.

    Here is how I deviated.
    First I needed a very specific type of screwdriver, a skinny flathead with a (>=)6" shank. I had other screwdrivers just as long but their shank was too thick or too short to work in such a tight space.
    Second I could not for the life of me pull out the retaining clip in the way instructed. I tried really hard but there was no getting around metal tubing that was in the way. Here's a picture to get an idea of things:


    Clip.jpg (alternate link)



    So I tried really hard to go with the screwdriver through that hole above, for a long time with a lot of patience but it wasn't happening. I could pop the clip out a tiny bit but not enough. I decided to reposition my screwdriver from the right side instead. Looking through the hole as seen in the pic above I was able to guide the screwdriver in from the right side and work on the clip. Here's a picture to get an idea of things:


    Screwdriver.jpg (alternate link)



    So at this point I was so frustrated I decided I was just going to bend the clip and even if it breaks I didn't care I would just have to wait until Monday and buy another one. So using my screwdriver from the position in the pic above, and with my left hand reached in (as described in step #2 from the directions) and feeling the clip, I was able not to slide it out, but rather to pop the right side leg out of its groove. It snapped back in a few times but repeating this process, and working and attempting to rotate the clip in its compromised position with my hand, I was able to get the clip to pop out. And luckily I was able to very patiently work it into my two fingers and take it out!

    The rest of the procedure was kind of difficult but nothing compared to removing the clip. When I removed the old sensor the old O-ring did not come with it, so I did what it said in the directions and stuck my thumb in the hole and coaxed it out. Nearly impossible without dainty hands.

    Replacing the sensor was a difficult because I tried a few times to get it back on and almost lost the new O-ring in the process. In hindsight a few more O-rings in case they fell somewhere would have been a good idea. It was hard to sit the new sensor as it should sit and even when I had it sitting right I wasn't sure if it was all the way in. But after careful deliberation of the before and after feel (make careful note of the before feel and orientation) I decided it was and proceeded to put the clip back on.

    Naturally I did not put the clip on in the same way I took it off. The major problem was that the clip was previously oriented towards the engine. Instead when I put it back on I made sure the horseshoe part faced the opposite way (towards the cabin). It was hard to get the legs to line up with the grooves initially and again I almost lost the clip a few times. But eventually it went on. Someone suggested tying dental floss around the clip so you don't lose it; that might work. I live on the edge and I didn't.


    Total time from prep to cleanup was several hours for me. I still don't know if this will solve P2181 but I'll make posts to this thread with any additional info. Hope this helps any of you out there in a similar situation.

    P.P.S. Also here's a general pic from taligentx of what a retaining clip looks like on a VW passat. They show metal but in my situation it was plastic. But if you want an idea click here to see their pic.

    P.P.P.S. Another interesting thread on P2181 can be found here.
    Last edited by passat03wagon; 07-30-2012 at 06:50 PM. Reason: remove outdated imagehost links

  2. Remove Advertisements
    VW Passat Forum
    Advertisements
     

  3. #2
    6th Gear
    Join Date
    Feb 2007
    Location
    Lehigh County, Pa.
    Age
    59
    Posts
    9,780
    Good post, pictures are always a bonus. I usually tell people to buy two clips along with the sensor; with the one already on there, it gives you three: One to use, one to break, and one to lose inside the engine compartment. All seem inevitable.

  4. #3
    3rd Gear
    Join Date
    Sep 2002
    Location
    Hannover, Germany
    Posts
    1,157
    Good write up. Your experience very much mirrors mine when I replaced the CTS. In my case, code p2181 returned again. I have since replaced the thermostat, and so far, have eliminated the code.

  5. #4
    Neutral
    Join Date
    Dec 2008
    Location
    Westchester, N.Y.
    Posts
    85
    The P2181 code reappeared today. It did not trigger in the last four months, driving some 30 miles every weekday.

    I'm curious as to whether or not the weather has anything to do with it, as the weather has been great up until today. It was the first cold day we had in the last four months. I find it odd that the first cold day we have the code is triggered.

    I've cleared the code and another pending (same) and now I'll wait and see if it reappears tomorrow.

    What do you guys think? I really don't want to mess with that thermostat!

  6. #5
    Neutral
    Join Date
    Jan 2010
    Location
    APO, AE
    Posts
    11

    It worked for me (CTS replacement 1.8T AWM)

    Thanks for the post -- especially the pics. I've gone out to do this repair several times and returned because I couldn't find the sensor.

    I used your method in combination with the other AWM write-up. I could get the retaining clip to 'unspring' but not completely come out -- there's literally no way to pull it when inserted from the engine-side. The following worked for me and thought I'd add it here for others trying to do it.

    Removing retaining clip: If you can pry it out enough so it doesn't spring back in, then put the new clip (lowered by dental floss from above) in from the firewall side and the old one pops falls out of the housing; remove the new clip and continue with replacing the sensor.

    Use a small LED light from the bottom (when you're doing the reach around step in the AWM post) to confirm you've got the right sensor and for initial prying from above. I could not get light on it from above.

  7. #6
    2nd Gear
    Join Date
    Feb 2007
    Location
    SW Ontario
    Age
    51
    Posts
    580
    Brings back memories, I was cursing the Hungarians that built this engine and had the nerve to install the clip backwards !! I shit in your Goulash !!

  8. #7
    1st Gear
    Join Date
    Jun 2008
    Location
    King of Prussia Pa
    Posts
    162
    I TOTALLY AGREE! I just have to give up based on time constraints. What A-hole at VW decided it was a good idea to position the clip that way! I started going "Clark Griswold" crazy when I saw that the clip had groves on it for gripping only you couldn't get your fingers on it!

    Quote Originally Posted by passat03wagon View Post
    Second I could not for the life of me pull out the retaining clip in the way instructed. I tried really hard but there was no getting around metal tubing that was in the way. Here's a picture to get an idea of things:

    So I tried really hard to go with the screwdriver through that hole above, for a long time with a lot of patience but it wasn't happening. I could pop the clip out a tiny bit but not enough. I decided to reposition my screwdriver from the right side instead. Looking through the hole as seen in the pic above I was able to guide the screwdriver in from the right side and work on the clip. Here's a picture to get an idea of things:

    So at this point I was so frustrated I decided I was just going to bend the clip and even if it breaks I didn't care I would just have to wait until Monday and buy another one. So using my screwdriver from the position in the pic above, and with my left hand reached in (as described in step #2 from the directions) and feeling the clip, I was able not to slide it out, but rather to pop the right side leg out of its groove. It snapped back in a few times but repeating this process, and working and attempting to rotate the clip in its compromised position with my hand, I was able to get the clip to pop out. And luckily I was able to very patiently work it into my two fingers and take it out!

    The rest of the procedure was kind of difficult but nothing compared to removing the clip.

  9. #8
    1st Gear
    Join Date
    Jun 2008
    Location
    King of Prussia Pa
    Posts
    162

    tip

    If you drop the retaining clip into the engine compartment by accident just gun the car in forward and reverse a few times and it will fall out like mine did. When putting it back on tie string from the clip to your finger.

  10. #9
    Neutral
    Join Date
    Dec 2011
    Location
    Glens Falls NY USA
    Posts
    40
    Have same engine with 107,000m. Got P2181 code. In my dumber days, dealer previously replaced sensor at 76,000 m at astounding cost. Tried deleting code but came back after a while. After reading posts at various web sites and because of the mileage, I replaced the sensor ($9) with not too much trouble, the thermostat & its O ring ($11) .... which later tested good on the kitchen stove using a cooking thermometer [??], did a good flush job including heater core, and replaced coolant with 5yr/100,000m Prestone (1 gallon at $10) using a web-site recommended 40/60 mix distilled H2O. After a few days the mix tested good to minus 25 degrees - okay for my location. Been a while and everthing is good so far. Tho temp gauge always/previously read btwn 175-190 and heater wk'd good, the engine now heats up faster and heater really puts out HOT air without any signs of system overheating. Personally, think main problen is these sensors are very touchie. My OEM thermo was a 180 degree and worked okay; and even at 107,000 my system and OEM G12 coolant was very clean/tested good.

  11. #10
    1st Gear
    Join Date
    Mar 2012
    Location
    Detroit
    Posts
    394
    Quote Originally Posted by passat03wagon View Post

    So at this point I was so frustrated I decided I was just going to bend the clip and even if it breaks I didn't care I would just have to wait until Monday and buy another one. So using my screwdriver from the position in the pic above, and with my left hand reached in (as described in step #2 from the directions) and feeling the clip, I was able not to slide it out, but rather to pop the right side leg out of its groove. It snapped back in a few times but repeating this process, and working and attempting to rotate the clip in its compromised position with my hand, I was able to get the clip to pop out. And luckily I was able to very patiently work it into my two fingers and take it out!
    Man! This scared the sh%$# out of me. Just this morning I bout a new CTS ($9) to replace mine next weekend. After reading this and others' comments, I think this is gonna be a hell day for me. I'm not sure why they put the components in such an impossible position but I tend to believe they do it on purpose so people just take the car to stealership and maximize their revenue.

    I'm sure there must be trick to get this job done easier and faster than several hours. But for now, I'm preparing myself for the battle. I once heard from an Indian that they have a proverb saying "when rape is inevitable, just lay down and enjoy!"

    P.S. the old thread's pictures are gone so it's useless.

  12. #11
    6th Gear
    Join Date
    Feb 2007
    Location
    Lehigh County, Pa.
    Age
    59
    Posts
    9,780
    Take heart. Maybe I just got lucky, but it didn't take me but half an hour on my AWM (the earlier ATW engine has the CTS right on top) I didn't particularly care for laying on top of the engine, with my arms reaching down up to the shoulder, but it worked.
    SleeperWagon likes this.

  13. #12
    3rd Gear
    Join Date
    Dec 2008
    Location
    Dallas, TX
    Posts
    1,209
    Quote Originally Posted by scotts13 View Post
    Take heart. Maybe I just got lucky, but it didn't take me but half an hour on my AWM (the earlier ATW engine has the CTS right on top) I didn't particularly care for laying on top of the engine, with my arms reaching down up to the shoulder, but it worked.
    Yeah, just lay on the engine. On AWM you'll be working blind mostly, I could barely see edge of the CTS while hugging the engine...snapped pictures to get a better idea how everything was set up (didn't have a mirror that would work well enough).

    30 mins to an hour if your first try, 15 mins on any future attempts. For me the clip was easy...connector for the sensor was tougher, mostly because I was worried about breaking it while jamming a flat-head in there blind.

  14. #13
    Neutral
    Join Date
    Sep 2009
    Location
    Seattle
    Posts
    20
    I just performed the operation myself... I found that the metal plumming on the head interfered with the clip sliding straight out towards me, so I had to bend it quite a bit- eventually causing it to break a couple mm off one end. I may get a new one eventually, but I didn't find that it prevented it from doing its job.

    What did I end up doing? I got frustrated bloodying up my fingertips trying to loosen it. I fished a long zip tie through the curved end of the clip (with a bit of floss tied to it for safety), then fastened it tight. The stem of the tie proved useful enough to shimmy the clip out with the help of a screwdriver wiggling the other side, another plus, the zip tie made it easy to recover the clip once it was free, as well as reposition it for installation since it is so stiff. I decided to just leave it attached to the clip for future ease of removal. Im guessing with the clip reoriented against the cab it wouldn't take more than a few minutes to replace in the future.

    I found that the metal plumming on the head interfered with the clip sliding straight out towards me, so I had to bend it quite a bit- eventually causing it to break a couple mm off one end. I may get a new one eventually, but I didn't find that the break prevented it from doing its job properly.

    I was surprised to see that the OEM sensor coming out was also green, like the newer replacement sensors. I drive an 04 1.8t AWM sedan.

  15. #14
    3rd Gear
    Join Date
    Dec 2008
    Location
    Dallas, TX
    Posts
    1,209
    04 AWM here too, pretty sure my original was green as well. I read somewhere on PW that reason for the color change was the old blue ones had known defects, changing color entirely let you know green is an updated one. Guessing by 2004 this had been figured out and green was used in manufacturing.

  16. #15
    1st Gear
    Join Date
    Aug 2010
    Location
    Rochester, NY
    Age
    53
    Posts
    304
    Did my 04 AWM with 150K and replaced the CTS two weekends ago, you think they could have put in a more friendly location?

    If clip releases towards firewall your CTS has been replaced but that doesn't mean it's not bad, they are a high failure item on our cars.

  17. #16
    Neutral
    Join Date
    Apr 2011
    Location
    Vermont
    Posts
    133
    What I did to keep track of that clip coming out, and going in, was to use an alligator clip with a length of bell wire attached to it. I simply clipped the alligator to the sensor clip at the bottom of the U where the ridges for gripping are. The alligator clip and wire gave me something to help pull the clip out of the engine compartment, and not drop it when fishing it back into the compartment after the new sensor was installed.

  18. Remove Advertisements
    VW Passat Forum
    Advertisements
     

Thread Information

Users Browsing this Thread

There are currently 3 users browsing this thread. (0 members and 3 guests)

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Powered by vBadvanced CMPS v4.1.2