P2181 Engine Coolant Temp Sensor - AudiForums.com
AudiForums.com

Go Back   AudiForums.com > Audi Models > Audi A4 > B7 Models
Search

B7 Models Please discuss all 2005.5 - 2008 B7 A4 topics here...



Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 10-26-2012, 11:45 AM
1st Gear
 
Join Date: May 2011
Posts: 5
Default P2181 Engine Coolant Temp Sensor

All:

I got this code and atemdpted to t=replce the sensors first. My problem was the temperature gauge was not working properly, however the heat is working properly and the car is not overheating.

I replaced one of the sensors the 06A-919-510-A however the tech at the Audi dealership said the one they susually replace is the 059-919-510-A. The problem I have right now is where is it located in my car (2.0T).

The data available at the delaership sucks too, it just from the 2.0T schematic to the 1.8T schematic like if they were the same. The 1.8T shows both sensors but the 2.0T is not clear on that.

The sensor I changed deals with the heat inside the car, but not with the gauge. From what I've read the next step if the sensors don't fix it is the thermostat.

Any help in locating the other temperature sensor is greatly appreciated.
Reply With Quote
  #2  
Old 10-26-2012, 02:54 PM
Damaniac311's Avatar
1st Gear

 
Join Date: Apr 2012
Posts: 93
Default

Click the image to open in full size.
Click the image to open in full size.

Hopefully that helps.

When I had this code come up, I replaced that sensor first. Didn't fix the code.
Then I had my timing belt service done because it includes the water pump, and I was due for the service anyway. Didn't fix the code.
Then I read somewhere that a missing belly pan could cause this because when outside temp is cold and there's no belly pan, then the cold air rushes into the engine bay throwing off the sensors. I had lost my belly pan the previous winter due to it cracking off from ice buildup. Got a new belly pan and installed it. Helped the temp guage a bit, but still the code came back.
Finally I decided to tackle the thermostat myself. Well sure enough it was stuck. New thermostat, car gets up to operating temp quickly and stays there. Haven't gotten the code since.

So, I would certainly start with the coolant temp sensor since it's cheap and relatively easy to replace. But if it doesn't fix it, you see what I had to go through. If you're not due for timing belt service I'd go right for the thermostat. About $100 and a couple hours of your time.

Good luck
Reply With Quote
  #3  
Old 10-26-2012, 05:55 PM
Audi Tek's Avatar
Tech Certified
 
Join Date: Jul 2009
Location: Connecticut
Posts: 766
Default

its the thermostat.

2181 is cooling system malfunction fault, not coolant temp sensor.

I actually did one today
__________________
Master Audi Technician.
Please provide your VIN number for faster reference in PMs or threads asking for help. Thanks
Reply With Quote
  #4  
Old 10-28-2012, 04:22 PM
1st Gear
 
Join Date: May 2011
Posts: 5
Default

Thanks for the responses. I'm planning to replace the thermostat. Any recommendations about what brand to purchase? I've heard about BEHR, dbcperformance, etc.

Any help is greatly appreciated.
Reply With Quote
  #5  
Old 11-19-2012, 04:27 PM
1st Gear
 
Join Date: May 2011
Posts: 5
Default Thermostat replacement instructions

I finally received teh thermostat from bdctuning. Are there any good instructions for its replacement?

Thanks,
Reply With Quote
  #6  
Old 12-02-2012, 02:29 AM
1st Gear
 
Join Date: May 2009
Posts: 68
Default

Thermostat Diagnosis/Replacement Technical Questions
Reply With Quote
  #7  
Old 08-01-2013, 12:40 AM
1st Gear
 
Join Date: Aug 2013
Posts: 1
Default

So does the 2181 mean thermostat is not working? I have a 2008 audi TT 65K miles and had the same problem. Changed the sensor, it went away for a while and it came back. Temp gauge is not working again. You reset it and goes away for a while but comes back again.
What should i do? comments would be appreciated.
thx
Reply With Quote
  #8  
Old 08-01-2013, 08:06 AM
1st Gear
 
Join Date: May 2011
Posts: 5
Default Thermostat

The best thing you can do is to replace the thermostat. You can find it for about $60 and it will take you about 2 hours and a bigvjug of coolant to fix it. There is a link for work instructions for the 2.0T. That will get rid of the issue you have. Hope that helps you.
Reply With Quote
  #9  
Old 08-01-2013, 08:30 AM
2nd Gear

 
Join Date: May 2010
Posts: 553
Default

Yup, definitely replace the t-stat. I also tried the temp sensor first and the code went away for a little, but came back. New thermostat fixed it right up.
Reply With Quote
  #10  
Old 06-10-2014, 05:37 PM
LuccaT's Avatar
1st Gear
 
Join Date: Jun 2014
Posts: 1
Default

I being having the same issue on my Audi a4 quattro 2008!
light came on and the temp gauge is marking right in the middle!
code p2181..read all the comments and i still dont know what to replace!
cooling sensor or thermostats?
somebody know the part number for both?
Reply With Quote
  #11  
Old 06-11-2014, 08:52 AM
1st Gear
 
Join Date: May 2011
Posts: 5
Default

My best advice is to start with the cheapest of the fixes which are the temp sensors. The 2 part numbers are on the first message in this thread. The only problem is that if that doesn't fix it, you will have to go for the thermostat, and the dealership will not return the money to you for the sensor.

You can buy the thermostat in the autoparts warehouse and i even have a coupon if you want it.

Thanks
Reply With Quote
  #12  
Old 02-09-2015, 12:48 PM
1st Gear
 
Join Date: Sep 2007
Location: South florida
Posts: 65
Default Revisiting for clarification

Sorry to revive this old thread. I've had the P2181 code show up and I need some help to track down the cause. I have reset the code and it hasn't come back yet (after a week), but I can tell from looking at the thermal gauge something is not normal.

Is there any way to diagnose the cooling system to narrow down the cause to either a bad sensor, or a thermostat?

It seems if the thermostat was stuck closed the car would boil over, but I haven't had any boiling problems. It could possibly be stuck open, but from my experience, when the T_Stat is stuck open the car may take longer to heat up but the coolant temperature would still rise to normal operating temperature after a while (especially down here in south Florida). However in my case the temperature gauge is just not getting all the up to the normal range (just over the half-mark), it is about 1/8 to 1/4 lower than normal.

I'd like to avoid doing the t-stat if I don't have to, it is a fairly involved task to get at. It would be great if there is some what to test the resistance or something on the sensors to determine if one of the sensors is failing.

Anyone know or have any thoughts how to verify what the cause might be?
Reply With Quote
  #13  
Old 02-09-2015, 03:40 PM
1st Gear
 
Join Date: Jul 2014
Posts: 56
Default

Quote:
Originally Posted by SFL_A4 View Post
Sorry to revive this old thread. I've had the P2181 code show up and I need some help to track down the cause. I have reset the code and it hasn't come back yet (after a week), but I can tell from looking at the thermal gauge something is not normal.

Is there any way to diagnose the cooling system to narrow down the cause to either a bad sensor, or a thermostat?

It seems if the thermostat was stuck closed the car would boil over, but I haven't had any boiling problems. It could possibly be stuck open, but from my experience, when the T_Stat is stuck open the car may take longer to heat up but the coolant temperature would still rise to normal operating temperature after a while (especially down here in south Florida). However in my case the temperature gauge is just not getting all the up to the normal range (just over the half-mark), it is about 1/8 to 1/4 lower than normal.

I'd like to avoid doing the t-stat if I don't have to, it is a fairly involved task to get at. It would be great if there is some what to test the resistance or something on the sensors to determine if one of the sensors is failing.

Anyone know or have any thoughts how to verify what the cause might be?
It's not going to boil over, especially if your in cold temps. Sometimes some coolant will get to the heater core because the tstat isn't totally stuck, but your temp sensor still won't register fully warmed(middle). You still may get heating as well, but usually that code will start appearing more frequently as miles progress.

The fault code and the temp gauge at 1/4 the way is definitely your tstat. Part isn't expensive, just coolant and thermostat. Should be able to do this in a afternoon. Check the DIY thread on this here on audiforums.

Last edited by Dolamite; 02-09-2015 at 03:42 PM.
Reply With Quote
  #14  
Old 02-10-2015, 09:47 AM
1st Gear
 
Join Date: Sep 2007
Location: South florida
Posts: 65
Default

Quote:
Originally Posted by Dolamite View Post
It's not going to boil over, especially if your in cold temps. Sometimes some coolant will get to the heater core because the tstat isn't totally stuck, but your temp sensor still won't register fully warmed(middle). You still may get heating as well, but usually that code will start appearing more frequently as miles progress.

The fault code and the temp gauge at 1/4 the way is definitely your tstat. Part isn't expensive, just coolant and thermostat. Should be able to do this in a afternoon. Check the DIY thread on this here on audiforums.
Thanks Dolamite. I guess I was hoping for something a little more definitive in terms of narrowing down the likely cause. Bear in mind, I'm in south Florida, where the average daily temperature is 80F degrees, and I drive 100 miles daily in traffic, so a stuck thermostat in the closed position would certainly give some indication beyond a low gauge I would think.

If you have a link to that DIY I would greatly appreciate it as I haven't found any for the A4 B7 2.0T Quattro MT6. I'm not sure of the variations, there seems to be DIY instructions for the 1.8T, but I don't know how different they are from my A4.

Is there any way to test the sensors? Perhaps a resistance test?
Reply With Quote
  #15  
Old 02-10-2015, 11:11 AM
2nd Gear

 
Join Date: May 2010
Posts: 553
Default

Quote:
Originally Posted by SFL_A4 View Post
Thanks Dolamite. I guess I was hoping for something a little more definitive in terms of narrowing down the likely cause. Bear in mind, I'm in south Florida, where the average daily temperature is 80F degrees, and I drive 100 miles daily in traffic, so a stuck thermostat in the closed position would certainly give some indication beyond a low gauge I would think.

If you have a link to that DIY I would greatly appreciate it as I haven't found any for the A4 B7 2.0T Quattro MT6. I'm not sure of the variations, there seems to be DIY instructions for the 1.8T, but I don't know how different they are from my A4.

Is there any way to test the sensors? Perhaps a resistance test?
Thermostats don't typically stick closed. Based on it never getting up to temp and the code, I'm 99% sure this is your thermostat. Typical operating temp for this car is around 200F, so even in the 90F summer temps of Florida, you're probably not going to get it up to 200F with the thermostat stuck open all the way and circulating constantly.

The only way to know if it's the sensor without doing the work of changing the thermostat is to change the sensor first (it's easier to get to) and see if the problem goes away. It probably won't, you'll be out the $50 for the sensor, and you'll end up back where you started.

Search is your friend: B7 Thermostat DIY

It's more than I wanted to tackle in my driveway, so I paid a shop (I think) around $300 to do it. Audi wanted nearly twice that.

Last edited by KingWulfgar; 02-10-2015 at 11:16 AM.
Reply With Quote
  #16  
Old 02-11-2015, 09:28 AM
1st Gear
 
Join Date: Sep 2007
Location: South florida
Posts: 65
Default

Quote:
Originally Posted by KingWulfgar View Post
Search is your friend
Thanks Wulfgar.

I'm getting a little better at searching the forum, but not sure how to limit searches to B7 models, it seems when I search a get a lot threads from other models.
Reply With Quote
  #17  
Old 02-11-2015, 10:12 AM
2nd Gear

 
Join Date: May 2010
Posts: 553
Default

Quote:
Originally Posted by SFL_A4 View Post
Thanks Wulfgar.

I'm getting a little better at searching the forum, but not sure how to limit searches to B7 models, it seems when I search a get a lot threads from other models.
I don't either. I just skim the forum column of the search results to find threads from the B7 forum. That one, I had seen pop up recently, so I sort of knew what I was looking for.

Good luck with it. I really do think it's your t-stat and if you're up for the task, people have said it's not that hard to change. Personally, I have multiple left thumbs and always end up breaking something worse when I try stuff like that, so I left mine up to the professionals.
Reply With Quote
  #18  
Old 02-11-2015, 10:51 AM
1st Gear
 
Join Date: Jul 2014
Posts: 56
Default

Quote:
Originally Posted by KingWulfgar View Post
I don't either. I just skim the forum column of the search results to find threads from the B7 forum. That one, I had seen pop up recently, so I sort of knew what I was looking for.

Good luck with it. I really do think it's your t-stat and if you're up for the task, people have said it's not that hard to change. Personally, I have multiple left thumbs and always end up breaking something worse when I try stuff like that, so I left mine up to the professionals.
It's not hard at all. The worst part was that lower radiator hose, use the WD 40.

Get the Mahle Bahr t-stat from ecstuning.com. They're Audi's actual supplier, this one is the exact thing, just doesn't have the audi stamp and is much cheaper.

DON'T get the Wahl t-stat, they've been known to leak.

FCPeuro.com is having a G13 coolant on sale for the next two weeks. $19 for a gallon!! That's a thirty dollar value. Don't put anything but G13 or G12 coolant, it'll mess things up.

If you have any questions on the process, feel free to PM me.
Reply With Quote
  #19  
Old 02-17-2015, 09:11 PM
2nd Gear
 
Join Date: Oct 2009
Posts: 562
Default

When my car threw that code, it was a bad thermostat. Up in a Michigan winter, when it sticks open, your engine won't warm all the way up, and the heat, though it keeps the car ok, doesn't have much reserve. The heat was maxed out, and kept the car barely comfortable, but not much more. Force the heater to the HI position didn't make much difference. I also noticed a drop in gas mileage since the engine couldn't warm up all the way.
__________________
B7Night

2006 Black A4 quattro 2.0t FSI 6sd man
Reply With Quote
 
 
 
Reply


Tags
05, 2005, 20t, 2181, a4, audi, code, coolant, dirty, error, nashville, p2181, sensor, temp, temperature


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Which one is Engine coolant temp sensor xewax Audi A6 2 10-28-2009 06:06 AM
Engine coolant temp sensor xewax Audi A6 1 10-07-2009 09:21 AM
Engine Coolant Temp Sensor audiA4gm B5 Models 2 02-18-2009 07:36 PM
where is the engine coolant temp sensor in my 01 A4 V6? elphlako General Tech 2 12-01-2006 12:34 AM
Engine coolant temp sensor wyldstallian Audi A4 1 12-26-2005 12:55 AM

 
Advertising
Featured Sponsors
Vendor Directory
Our Sponsors
All times are GMT -4. The time now is 03:49 AM.

Internet Brands, Inc.
Emails Backup