# Code P2185 Engine coolant sensor circuit high voltage 2005 VW Jetta 2.5



## assnow1 (Jul 16, 2009)

I have had my 2005 Jetta 2.5 5cyl(32k mi) for about 18 months now and have only replaced the engine coolant sensor, besides normal maintenance. Now I am getting a P2185 code. I am going to flush my coolant and fill it up again. If that does not work anyone have any ideas where I should look next? water pump? At first I was thinking thermostat but the chances of that being the problem, from what I have read, is slim to none if at all. Could anyone provide some tips or helpful hints?


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## Unilateral Phase Detractor (Aug 23, 2005)

*Re: Code P2185 Engine coolant sensor circuit high voltage 2005 VW Jetta 2.5 (assnow1)*

Check your radiator fans for proper operation. They may have failed and thus you can overheat and cause this code.


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## assnow1 (Jul 16, 2009)

I have noticed that the fans are operateing at a higher rate since I changed my radiator fluid out. About every 20 minutes over so they will overspin, as they are trying to catch up and cool quicker. I am going to change the fluid again with the same fluid the dealer and import techs suggested this weekend. Would using the wrong radiator fluid cause the fans to operate incorrectly? Thanks for responding i will keep the thread open and keep everyone posted.


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## HIBB 304 (Nov 8, 2008)

*Re: (assnow1)*

I think one of your fans is not working,causing the rapid speed of the other fan try to pick up the slack. Just my .02


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## assnow1 (Jul 16, 2009)

I let my car run for an hour and continuously checked the fans on the radiator and both seem to be working correctly and no overspeed thus far. hmmm


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## CorradoG602 (Jan 22, 2007)

*Re: (assnow1)*

there are 2 sensors, one on the lower rad. hose. Both are the same sensor.


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## assnow1 (Jul 16, 2009)

*Re: (CorradoG602)*

What exactly does that mean to me? Should I change the other sensor and see what happens as well? I am not sure what your post means to me (someone who has never worked on cars before). Any additional info would be very helpful. Thanks


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## Unilateral Phase Detractor (Aug 23, 2005)

*Re: (assnow1)*

It's probably not the sensor unfortunately. You can try changing it but pretty much everybody else who has had fan problems ended up replacing the fans themselves.


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## CorradoG602 (Jan 22, 2007)

*Re: (classicjetta)*

P2185 is not a fan control module fault. It even says it with the code he put. If the code was pulled with a vagcom it should say which coolant temp sensor it is. G62 is the ECT on the flange and G83 is the sensor that is on the lower radiator hose on the drivers side just below the fan harness. And if you get a cooling performance fault P2181 that means the T-stat is bad


_Modified by CorradoG602 at 10:51 AM 7-21-2009_


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## assnow1 (Jul 16, 2009)

*Re: (CorradoG602)*

Actually I did get the code for the Eng Coolant temp sensor 2 before and replaced the sensor. Now I am getting the high voltage code for the same temp sensor so I should keep looking for the t-stat? I did buy one and was going to replace it. I should continue with this correct?


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## DunKeL GraU (Jul 12, 2008)

I have the same P2185 code and have replaced both coolant temperature sensors. I still have the code. 

I recently replaced the large cooling fan because I threw that code and the code has disappeared so I know it's not the big fan.

The fans are still running loud so I am going to either try the DIY about cleaning the brushes but ill probably just replace the small fan and see if that fixes the p2185 code. I'd hate to do all that work to take the fan out and clean then put it back and then have to take it again. 

BTW my fan issue is that both come on at the same time, even when the car is cold. 

I'm open to suggestions so feel free to chime in.


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## LampyB (Apr 2, 2007)

how's your temp gauge in the car looking? does it always stay in the middle?


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## DunKeL GraU (Jul 12, 2008)

LampyB said:


> how's your temp gauge in the car looking? does it always stay in the middle?


Yes, always dead center. Even on the hottest of days.


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## DunKeL GraU (Jul 12, 2008)

Update: 

So today I was able to replace the smaller cooling fan but I still have e P2185 code. So after replacing both fans and both coolant temp sensors it is still throwing the code. I'm not sure where to go from here, I wonder if it's a wiring issue or something. 

I am getting these codes through an OBD2 reader not a vag-com, I wonder if that makes a difference. I think it might be time to take it into the shop.


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## DunKeL GraU (Jul 12, 2008)

Bump, hoping for some suggestions.


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## DunKeL GraU (Jul 12, 2008)

BUMP, anybody throw this code and have fixed it??


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## spitpilot (Feb 14, 2000)

I have been chasing this code for a year or so...first replaced both coolant sensors (VW's have had sensor failures for years...changed several)...but code came back..figured I got a faulty sensor so I returned the first two and replaced them a second time..all was well..till cold weather...then it cropped up again...I read a tech bulletin from VW about "contact issues" telling mechanics to try "stablant 22" prior to any component replacement when dealing with electrical issues...so I got some of this stuff and applied it to the terminals and connectors for the sensors..seemed to cure the issue...till now...cold weather crops up again...I get low temp reading on my guage (normal is 190)...and CEL pops on...when weather warms up...temp returns to normal steady 190 and CEL goes away after a few start up warm up cycles. I know this has to be a contact issue since the temp reading can jump from slightly low to spot on 190 just during running a few errands...there is a connector (connector 7) in the engine compartment that the lower temp sensor wire goes to...trying to locate that and treat it with Stablant 22 to see if that will eliminate this permanently!

Can anyone point out connector 7 in the engine compartment..suspect it's one of several that are down behind radiator in front of battery box..but which one?


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## SumDirtyVW (Dec 9, 2012)

i must bring this thread back to life. im running into the same problems with my fans being on all the time as fast as they can go. i tried different fans from another MK5. changed everything coolant sensor and cannot figure it out. any clues out there what might be the problem?


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## SumDirtyVW (Dec 9, 2012)

*hehe*

bump


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## Ronny Bensys (Apr 17, 2014)

Possibly the ECU determined that the sensor resistance is out of specs. That could go beyond the specified maximum when the wiring or connector is bad which will increase the total resistance. Check connector and the sensor to ECU wiring.


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## Zen_Affleck (Dec 3, 2020)

car was running perfect for almost 2 years, no codes or anything until I noticed something strange. the ac was warm and the temp was rising out of nowhere, I noticed the fans werent on. replaced the fcm and boom solved that issue, but I decided to change the coolant sensor while I was right there. all of a sudden im in limp mode and got my first check engine since having the car! idk what the issue is, i suspect i may have damaged the harness/clip some how. I think coolant got into it, what do you guys think? code p2185 amongst others, but I’ve only messed with the coolant temp sensor


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