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Old 05-15-2011, 07:23 PM
patparkerRegistered Member patparker is offline
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Join Date: May 2011

I have the problem with a 2004 Jetta. Each time I cleared the P2181 code, the engine light came back on after about 60 miles. I changed the CTS (original had green top, I relaced with another green top CTS). I cleared code and the light went away for about a week (over 300 miles of driving - long enough for me to pass an inspection). Then the engine light came back on. The fact that the light remained off for 300 miles telle me that changing the CTS had some impact, yet the light eventually returned. What a pain.
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Old 05-18-2011, 12:48 PM
RUGsux72Registered Member RUGsux72 is offline
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Join Date: Jul 2010
Car: 03 Turbo S Convertible, 10 Tiguan, 63 Beetle, 98 Jetta TDI

Originally Posted by patparker View Post
I have the problem with a 2004 Jetta. Each time I cleared the P2181 code, the engine light came back on after about 60 miles. I changed the CTS (original had green top, I relaced with another green top CTS). I cleared code and the light went away for about a week (over 300 miles of driving - long enough for me to pass an inspection). Then the engine light came back on. The fact that the light remained off for 300 miles telle me that changing the CTS had some impact, yet the light eventually returned. What a pain.
After 3 years of "chasing" this code I have found that the main reason for it is "slow to reach normal operating temperature". I too ran across resetting cel and sometimes 60 miles, sometimes 400miles, she'd come back on. I found on thos 400 mile times the weather was warmer, thus it reach N.O.T. faster. In end, I finally changed the stat, which I knew was the problem thanks to VAGCOM, but was too lazy to contort my hands to do it. Been P2181 free since November 2010 (knock on wood).
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Old 05-18-2011, 07:03 PM
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simonsiRegistered Member simonsi is offline
Join Date: Oct 2009
Auckland, New Zealand
Car: 2000 NB 2.0

Originally Posted by patparker View Post
The fact that the light remained off for 300 miles telle me that changing the CTS had some impact, yet the light eventually returned. What a pain.
Assuming a good CTS that code is "measuring" a problem in the cooling circuit, that is made up of coolant, passages/pipes/rad/block, water pump and thermostat. Assuming your coolant level is good then the thermostat is by far the easiest to change out to prove good or bad.

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Old 07-01-2011, 06:38 PM
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snglbnyRegistered Member snglbny is offline
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Join Date: Jan 2010
Kansas City, USA
Car: 2004 NBC Aquarius Blue

Hello Everyone,

Well, I'm on the P2181 Code wagon! I have a 2004 NBC and it just popped up about a month ago. I cleared it and it came back. So, I didn't want to do what happened to my Honda Accord (I blew the engine!) When Rich looked in the engine compartment, he really didn't want to take it on, so I finally went into VW and they said that it needs a thermostat replaced. Charged me $95 to tell me what I already knew and the cost to replace is $370! (also look at water pump while in there)($95 towards it).

(PS Rich has taken apart many engines and put them back together so it all is not foreign to him, just the fact that my VW compartment is SO compact!)

So my husband found your site through a search for the code and saw everything that you all are going through. He has a thermalcouple that can measure temps. We are thinking of doing that like what was mentioned on page 1 to see if water pump is working okay.

My question for you all is how do you get into the engine compartment without being a contortionist? We don't have a "service" manual. Any pictures/video to see to help in doing this ourselves?
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Old 08-02-2011, 02:25 PM
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Jeff2Registered Member Jeff2 is offline
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Join Date: Aug 2011
Car: 2005 Cabrio GL

I've got this code too, just one day after we bought our 2005 Beetle with the 2.0 engine. Ugh!
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Old 08-23-2011, 03:56 PM
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Hulker28Registered Member Hulker28 is offline
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Join Date: Jul 2008
Newburgh,, NY, USA
Car: 2004 Beetle Conv

Originally Posted by esse10 View Post
was your thermostat staying slightly open? what do you mean by failsafe thermostat?
If the thermostat fails, it stays open, I just went and got an oem stat.
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Old 08-23-2011, 04:24 PM
MyOtherRidesAVette's Avatar Member Sponsor MyOtherRidesAVette is offline
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Join Date: Nov 2010
Houston, TX, USA
Car: '05 Vert "Dark Flint Limited Edition"

This might help those trying to diagnose this code -

From Ross-Tech Wiki


18613/P2181/008577 - Performance Malfunction in Cooling System

Possible Solutions
  • Check Engine Coolant Temperature Sender (G62)
  • Check Coolant Thermostat
  • Check Engine Cooling System
    • Put the key on, fan speed on 1, and push the a/c switch. Are both fans kicking on? If not, you found the problem.
    • Put the key on and fan speed on 1 with temperature set to hot. Does heat come out readily from the vents?
      • No. Probably the water pump is gone.
      • Yes. Probably the thermostat is gone.
Special Notes
  • Check the stored Freeze Frame data with this fault code. Freeze Frame information will be found in the fault code description (if the module supports it) or in Generic OBD-II if the vehicle complies with those regulations.
    • Freeze Frame data stored at -40*C is generally an indication of a faulty ECT or wiring.
    • Freeze Frame data stored at +140*C is generally an indication of a faulty ECT or wiring.
    • Freeze Frame data stored with in the 68*C ~ 80*C range is an indication that the vehicle was close to, but not within, the cooling systems normal operation range. The Thermostat itself or Cooling system components may be at fault.
Retrieved from "18613/P2181/008577 - Ross-Tech Wiki"

In der Automobil-Scheune
'02 NBT, A/T, Moonroof, Platinum Gray, Flannel Gray Leather Interior (Currently on the slab in the morgue, possible ressurection in the offing)
'05 NB Convertible, Tip 6sd, Dark Flint Gray Edition, Garnet Red Top, Bordeaux Red Leather Interior
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Old 08-23-2011, 08:56 PM
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pueblorradoRegistered Member pueblorrado is offline
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Join Date: Dec 2006
Pueblo, CO, USA
Car: 2003 Beetle Turbo S

I just started throwing this code again, this is the 3rd or fourth period of time it has started coming on. again after i clear it, on a cool morning jumping straight on the highway it will come on after a couple miles. it seems to be excessive flow through the thermostat, in cases where the car is at highway speeds immediately after starting on a cool engine, that it fails to reach normal operating temperature fast enough and sets the code. I think a defect of design with the thermostat will cause, after time, the flow of coolant to be excessive, i.e. when there should be no circulation to get the engine up to operating temp, there is still coolant traveling the circuit. My occurrence is with an 03 turbo S. not sure if the thermostat is the same part number. Additionally, this condition doesn't occur with greater or less frequency during cold winter months, which seems to disagree with my thinking here, but it is all i can come up with.
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Old 12-11-2011, 05:22 PM
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elleteaRegistered Member elletea is offline
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Join Date: Nov 2011
Phoenix, AZ, USA
Car: 2004 NB 1.8L Turbo Convertible, Mellow Yellow

My CEL came on the other night driving on the freeway in the snow. This was the first time I have driven in snow and wonder if the cold wetness and the higher speed could have triggered this?

Had AutoZone check and got a 2181 code. My question is how long is safe to drive this way? I will be visiting my parents in a couple of weeks for Christmas and I think I can get my dad to replace the coolant temp sensor for me. The bad part is that's a 2 and half hour drive. Am I ok to make the trip?
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Old 04-24-2013, 02:01 AM
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sb_beetleRegistered Member sb_beetle is offline
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Join Date: Sep 2005
Solvang, CA, USA
Car: 2004 NBC 1.8T

I have an '04 1.8T with the P2181. I've cleared the code as no blinking coolant CEL. The code returns about half a day later. Today I smelled electrical after parking 8-0

Opened the hood and began pressing the fan fuses (attached to the battery box). Guess what? Fan kicks on when I press. Pulled the fuse (farthest left as facing the car) and it was corroded, nay blackened, by what I guess is some underlying electrical issue. Remember all of those who have had their fuses melt to the box or car burn to the ground as a result? I cleaned the contacts and the fan seems to kick in as expected. Going to keep a close eye on it. I'll post here with results and updates (if the 2181 returns or not).

Sent from App
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Old 04-07-2016, 11:55 PM
RuzukiRegistered Member Ruzuki is offline
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Join Date: Apr 2016
Car: Beetle 2003 GL 2.0L

Ive been lurking around this thread for a few months, ever since this code started popping up back in late November (I bought the car in October lol), figured Id finally make an account and post my experience so far.

I had this code come on often after cold mornings, and I just bought a scanner and kept clearing it, since I didn't have the money to fix it, and didn't want to just ignore the light and miss if something important came up. Clearing the code would sometimes only work for an hour, sometimes it would work for weeks. Completely random.

I had to replace the battery right before Christmas. Oddly enough, the car ran much better after, and the code stopped showing up. I figured all was well (or as good as it got with all the OTHER issues with the car).

Until my CEL came back on a week ago.
Guess what little f-er is back. That goddamn code.

Anyways, reading through the rest of this thread, I really think the problem is just that the VW people programmed the cars computer system stupidly, and entered too high of a value for the 'low end' of the optimal operating temperature. That's why a lot of us cant find out what is causing it. Because there isn't actually a problem.
And replacing censors and stuff is probably just doing the same thing that me resetting the code over and over did, it just cleared it for the time being, until the car decided it was still a problem again. That's why sometimes it seems like it works for a while. That's why my 'battery' thing seemed to work for months. It just cleared the memory or something, for a while, until the system checks caught it again.

Regardless of my own suspicions about the programming of the cars computer system, I do plan on going in and checking all of these censors and systems out at some point. I just haven't had the money or the time yet. I bought it off a friend in October, I haven't even finished making payments yet... And Ive been using this forum to teach myself all about the problems popping up and how to try to fix them...
Like when I took it in for an oil change and was told it had a really bad oil leak that was totally not caused by the oil filter, and totally turned out to be a f-ing cracked oil filter once me and my mechanic-ish friend got under the car... I learned how to change my own oil that day at least, and I learned a ton about the oil system in general.
And the clutch issues it had been having since I got it, that I had been researching, and I finally figured out just this week was the clutch slipping, which was pretty easy to diagnose tbh once it literally was taking like 20 seconds to accelerate to 40mph... But I learned how to check the brake fluid, and learned a lot about hydraulic clutch systems, and figured out it must've been that the flywheel and friction plate were shot. Its being fixed in a shop now since that is beyond my friends 'college automotive class' level skills lol. At least I got a really good deal on the repairs... Probably cause I knew exactly what I needed and sounded like I at least knew how to google.

Last edited by Ruzuki; 04-08-2016 at 12:06 AM..
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Old 04-08-2016, 02:15 AM
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billymadeRegistered Member billymade is offline
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Join Date: Oct 2005
Las Cruces, NM, USA
Car: 02' Turbo S

You can diagnose; the particular issue, by looking at the "freeze frame" info provided by a scan tool, look at the end of this page: 18613/P2181/008577 - Ross-Tech Wiki

Most of the time; we are seeing, a bad thermostat as the problem (stuck, open or binding, not opening fast or far enough). When was the last time; you replaced your thermostat?

Here are the specs; for your car, you could use a scan tool, to monitor the temps and see if your thermostat opens when it should.

Thermostat: Specifications Opening starts @ approximately .................................................. .................................................. .................................................. ............... 86°C (187°F)
Opening ends @ approximately .................................................. .................................................. .................................................. ............... 102°C (216°F)
Opening lift: .................................................. .................................................. .................................................. ......................... 7 mm (0.28 inch) minimum

A thermostat swap; is definitely something you could do yourself: (I would recommend replacing the plastic coolant flange, when you are in there)

Here is the service manual pages for the procedure:

Here are some videos; to give you a visual sense of the process:
Got a trouble code? Look it up; on the Ross Tech Wiki!

Need to find a VW part number? Look up here:
Then, use google; to find the best prices! :-)

Last edited by billymade; 04-08-2016 at 02:28 AM..
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Old 04-12-2016, 01:16 PM
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esse10Registered Member esse10 is offline
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Join Date: Nov 2008
Richmond, TX, USA
Car: 03 1.8 Turbo
Default thermostat

Originally Posted by Hulker28 View Post
If the thermostat fails, it stays open, I just went and got an oem stat.
Mine was staying slightly open but that was because of the crud after somebody mixed the wrong coolant with the VW G12 stuff. haven't had issues ever since replacing all the coolant with the correct stuff.
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Old 04-12-2016, 04:45 PM
jfojRegistered Member jfoj is online now
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Join Date: Nov 2012
Fairfax, VA, USA
Car: '03 Vert GLX 1.8t 6 speed Tip

Soft fail thermostats are a COMMON problem.

These engines should run around 96C, they may vary from about 90C-100C, but 96 is pretty typical.

I have seen these engine run as much as 35F too low at times.

If the thermostat is over 2 years old, it is likely soft and you must have a way to monitor the engine temperature.

OBDFusion and an interface is less than $30 and will monitor the engine coolant temperature. It sill also give you Freeze Frame data as well.
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