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P2181 - performance malfunction in cooling system... HELP!

65K views 42 replies 24 participants last post by  DBVeeDB 
#1 ·
VAG-COM Version: Release 311.2-N
Control Module Part Number: 022 906 032 EG
Component and/or Version: MOTRONIC ME7.1.1G 5626
Software Coding: 0000132
Work Shop Code: WSC 12599
1 Fault Found:
18613 - Performance Malfunction in Cooling System
P2181 - 008 - Implausible Signal
now the car is/was under warranty. i took the car in the first time, they replaced the CTS, gave me back the car, car was fine, few days later, light came back on, same code. took the car back again, they replaced the water pump and thermostat and thrmostat housing, they said the water pump impeller broke and damaged the thermostat. well they give me back the car, car seemed fine, then i noticed a day later that on cold start there was no elevated idle, thought to myself, the cel is gonna come back on, sure enough it came back on
. took it in again last night, they looked at it this morning and said the code came up, but when they tried to go through guided fault finding, that they couldn't find any causes for the cel. so they cleared the code, drove it for 36 miles to see if the cel would come back on, nothing, tell me to pick up the car, that they couldn't find anything. now i checked my fans before i dropped of the car last night and they were working, so idk what the problem is. here is where it gets tricky, i brought the car in last night with 49,968 miles, they give me back the car with 50,004 miles, now im out of warranty. i asked them if the cel comes back up and i bring it back if they are goin to warranty the problem, they said if its something wrong with the parts they replaced yes i have a warranty on them for 1yr/12k miles, if its something else causing it then no. i said well wouldn't u have to cover it since its a pre-existing problem, they said no, so instead of fighting i called VWOA and documented the problem, so if it happens, they should take care of me and cover it. so im gonna wait and see what happens in the next few days, i have a feeling that its going to come on again cause when i picked up the car it was cold, and there was no elevated idle.
does anyone have any idea what the problem could be? i don't think its the fans cause like i said they seemed to be working fine.



Modified by dave13s4 at 6:31 PM 12-12-2007
 
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#3 ·
Re: P2181 - performance malfunction in cooling system... HELP! (dave13s4)

Quote, originally posted by dave13s4 »
BUMP

have them check the coolant with a refractometer(not sure if i spelled that right) not a hrydrometer. If over the course of the vehicles life it has been topped off with straight coolant or improperly mixed coolant the mixture is probably not right. Have them add some water to it to get the mixture for about -25 as i bet you its sitting somewhere between -40 and -50 right now which is way to much.
hope you get it sorted out let me know what they find

Tommy


Modified by Ted Brogan at 10:40 PM 12-18-2007
 
#6 ·
Re: P2181 - performance malfunction in cooling system... HELP! (Ted Brogan)

i mentioned that to them, and they said the mixture was fine, and then told me that they spoke to vw's tech line, and they said the cause of my problem is my cold air intake, so the dealership told me to put the stock airbox on and that would fix the car. i argued that fact but said fine, ill put it back on for u, just to prove to u that the light will come back on and that ur wrong. well i took the car home on wed night, and sure enough the light came back on this morning, so i can't wait to get in touch with them on wed. they're gonna hate me, cause this is the 5th time for the same problem, and now im done being nice and patient.
 
#8 ·
Re: P2181 - performance malfunction in cooling system... HELP! (Ted Brogan)

I'm having the same problem, came up last night on the way home. I was driving about 75-80mph and it came on. temp gauge said 190 but from what i've seen that is incorrect. The T-stat has been changed and the water pump went out at 47K. I'm at 57K now. That being said, I am not missing the belly pan. However, i have driven through snow and ice here in texas last Feb. and it didn't come on. S-T-R-A-N-G-E!
Will check mixture tonight, maybe santa will bring me the "meter"!
 
#9 ·
Re: P2181 - performance malfunction in cooling system... HELP! (blackwolfjetta)

Bump this thread... I'm having the same problem here.
I replaced my black ECT with a new green ECT and cleared the code... took a while for it to come back - about 2 weeks or so. I thought it was some kinda fluke so I erased the code and kept my scanner in the car at all times. Cousin of mine who is a VW Tech mentioned to me that the coolant CAN throw the P2181 code.... so I flushed it out with a 50/50 VAG Coolant mixture. Light came back within 2 days....
Got me another green ECT and swapped it out on Friday right before I left work. Topped off coolant with pre-mixed 50/50 stuff and drove the car all weekend- 300 miles and today I decided to check the ECU, DTC pending- P2181.
I know when the code comes back, the car looses power and feels sluggish on acceleration. When the light finally comes on, the car feels reallllly slow. So I carry my portable scanner with me at all times.
WTF ?
Mods are GIAC chip, EVO CAI.
2 ECTs and coolant flush haven't fixed my problem. I love the car, I hate the check engine light !
 
#10 ·
Another Bump! Same problem here.
My Codes:
18613 P2181 232
Malfunction in Cooling System
(2004 VW R32)
Have about 60K miles on it. ECT replaced last year. Monitoring temp while driving, it only gets up to about 175F to 180F on very cold days. The fault appears near the end of engine warmup, usually while on the highway for me. Problem is intermittant -- but it now seems like it's always going to occur on cold days. Haven't done any serious troubleshooting yet because of the lack of available information.
Guess I'll check my fans (operating), then consider replacing the thermostat. Before going for the thermosat, however, I'd like to know what engine temps you folks see when warmed up and monitoring with a Vag-Com or equivalent system.
Thanks,
George
 
#12 ·
Re: P2181 - performance malfunction in cooling system... HELP! (dave13s4)

If one of the impeller blades is still in the cooling system, it could be getting caught on the t-stat keeping it from opening or closing all the way. The ECU will see that the coolant temp is not where it should be based on other inputs and throw a code. If the VW shop is flat rate, there is a good possibility that they did not flush the cooling system to get rid of any water pump debris. Just a thought. Good luck to you, and remember, the sqeaky wheel gets the grease
 
#13 ·
Re: P2181 - performance malfunction in cooling system... HELP! (Zba)

Im gonna stick with my original statement. Ive found lately on these cars that they have become very sensative to coolant mixture. 50/50 is to much coolant ive been doing about 60/40 with will protect it to about -25 and it takes car of the code on every single car....
Trust me on this one properly check the mixture with the correct tools set it to what i suggest and see what happens.
 
#14 ·
Re: P2181 - performance malfunction in cooling system... HELP! (Ted Brogan)

You may be right, Ted, about the antifreeze mixture causing a problem, but do you have any ideas about how or why that would trigger the computer to report a P2181 fault?
George
ps -- I did observe both my cooling fans come on during a long idle in the garage so I wouldn't think that is causing a P2181 fault in my case.
 
#15 ·
Re: P2181 - performance malfunction in cooling system... HELP! (R(ed)32)

Quote, originally posted by R(ed)32 »
You may be right, Ted, about the antifreeze mixture causing a problem, but do you have any ideas about how or why that would trigger the computer to report a P2181 fault?
George
ps -- I did observe both my cooling fans come on during a long idle in the garage so I wouldn't think that is causing a P2181 fault in my case.

Honestly i have no technical explanation as to why it causes it but for some reason it does lol.
 
#16 ·
Re: (R(ed)32)

Quote, originally posted by R(ed)32 »
but it now seems like it's always going to occur on cold days. Haven't done any serious troubleshooting yet because of the lack of available information.
Guess I'll check my fans (operating), then consider replacing the thermostat.

I have this same issue and I think it's the cooling fans.
If it only happens on cold days is that because you have the AC off on those days and ON when it's not a cold day?
My fans appear to function fine with the AC on @ idle.
However they don't appear to turn on to their low speed mode when they should (when the coolant reaches ~85-90 degrees c.) They kick on when the coolant temp reaches >100 degrees c but kick right off again when the car is <100 that's the high speed mode.
I'm not sure what is causing this problem though.
 
#17 ·
Re: (modulation)

Interesting link you posted in the R32 forum a few days ago regarding the high and low speed functions of the cooling fans. I know both my fans came on when idling in my garage, but I don't really know if it was slow or fast speed. Possibly fast only -- will have to check this out again with the a/c running.
My understanding is that the fan will come on (apparently in low speed) whenever the a/c compressor is run, and only go to high speed based on coolant temperature. If this is correct, I might have a low speed fan failure and that fault could be the possible source for the P2181 code.
George
 
#20 ·
Re: (20aeman)

This is an interesting problem, i have it as well P2181 Coolant Performance Malfunction. I have already replaced the coolant temp sensor, and the CEL went away for a week and a half, but its back on now. I've been talking to my guys at the dealer and they told me to replace the thermostat next, but before I do that i think im gonna replace the thermoswitch first clear the code and see what happens, after that if it comes back then ill go for the thermostat, I have observed that fans comming on at different intervals and temperatures so the thermoswitch might have a lot to do with it.....ill keep you guys posted.
Bump for a good thread http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif
 
#21 ·
It seems that in warmer weather, I'm not getting the P2181 code any more. Haven't replaced any parts or adjusted coolant level to change that. ???
Have confirmed that my low speed fans are not working. Fuses are okay, fast speed works, so I'm assuming that the low speed resistors in the fan motor assemblys are shot. (My digital volt meter has died, so no measurements there yet.)
I think this is a big problem -- on a long highway drive, I got held up in stalled traffic several times. On a 66F day, after about 10 minutes idling along, my high speed fans would energize. Plugged into the OBD computer to see what was happening and found that coolant temp was cycling between about 222F and 226F with an occasional spike to 230F. (This was with the A/C off.) Can't have that happening in hot weather! Ordered two of those power resistors that I'll mount externally to restore low speed fans.
George
p.s. At highway speeds with no fans, my coolant temp was pretty steady at about 184F.
 
#22 ·
Re: (R(ed)32)

I am having the same code p2181. I sat at the lower woodlands park today and let my car idle. I then tried to make my fan come on? I turned on the A/c and still no fan? What tells the fans to engerize? i checked the fuse and it looks alright.
 
#23 ·
Re: (kbs3)

The way I understand it --
The low speed fan will come on whenever the a/c is switched on regardless of temperature. Or it will switch on between about 198F and 206F, even if a/c is off. This is controlled by a thermoswitch.
The hi speed fan will switch on between 210F and 221F, also controlled by the thermoswitch. The fan controller deenergizes the low speed circuit when high speed is switched on.
The most probable failure you have is an open circuit in the power resistor inside each of the two fan motors. That will prevent low speed fans from running. If you are at operating temperature, and idling a while however, your high speed fans should kick in when coolant temp reaches the thermoswitch setpoint. (That's good, but, if you drive like that in hot weather, you'd better not use your a/c if you have to spend any time stopped or very slow. Some people have said that it's not good to run that a/c compressor without fan airflow around it.)
If it's the low speed resistors burned out, and you're still under warranty, get VW to replace both fans. A couple weeks ago, I used the DIY method and installed two 1 Ohm/100 watt external power resistors on an aluminum plate for a heat sink. This restores low speed fans, and it will probably last a lot longer than two new fans, believe it or not.
Finally, I have never seen any proof that the p2181 code is related to the cooling fans. Could be, but ? ? ? ? A month or two before I fixed my fans, I stopped getting the P2181. Didn't do anything to fix it. I think there's probably something not quite right about my system, but it only showed up during cold weather warmups for me.
p.s. When the fans come on in hi speed, they're plenty loud enough -- you'll hear them from inside the car. Low speed is pretty quiet -- you'll probably have to raise the hood and look to see if they're spinning.


Modified by R(ed)32 at 11:20 PM 5-28-2008
 
#24 ·
Re: (R(ed)32)

so get this... tonight i start my car with the radiator cap off. try to see if i can burp so air bubbles. now my car fluctuates a little bit from 185-190 degrees instead of just sitting at 190 all the time. i also sat there and let it heat up to 190 and still no fans. The damn thing won't over heat either.it just idles along and stays at 190 degrees. i also saw the fans turn on with the a/c so i know at least part of the system works. i am more lost then ever. i am thinking of just getting a new time belt, metal propelled water pump and whatever else and just living with it on my credit card...
 
#25 ·
Re: (kbs3)

In an earlier post I mentioned that when stalled in traffic, my actual temperature monitored via OBD went up to 230F. The dashboard temp gage needle never left 190F. That gage doesn't reflect accurate coolant temperature. It's more of an idiot light and not useful to show you what's really going on.
 
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