Engine Coolant Temperature Sensor - P2185

Recently, I had to replace my radiator fans (to the tune of $1000) because the small fan had stopped spinning and the large fan was making a very loud noise. It turns out that the fans had failed because they had been spinning at full speed all the time due to this fault:

008581 - Engine Coolant Temp Sensor on Radiator Outlet (G83): Signal too High
P2185 - 002 - Lower Limit Exceeded
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Mileage: 127849 km
Time Indication: 0
Date: 2000.00.00
Time: 13:02:42

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: 47.0°C
Temperature: 33.0°C
Absolute Pres.: 990.0 mbar
Voltage: 12.319 V

The sensor (on the lower radiator hose on the drivers side) has been replaced and the code cleared but when turning the car on, P2185 comes up again and the radiator fans are spinning at 100%, even on a chilly winter's morning.

Has anyone experienced this problem also? The dealership is recommending a pin-out test to check the wiring harness but I was wondering what else could be causing the problem.

Thanks everyone!

There are 2 coolant temp sensors, the other one's located near the high pressure fuel pump.

It seems your thermo's been closed.

Thanks for the response. Actually, looking at the work order, both the upper and lower sensors were replaced.

About the thermostat getting stuck closed, I've read that would cause a P2181 error code, no?

being thermo closed, cooled water does not circulate into the engine, so the secondary sensor always measures hot temperature. i think.

I found the pic.

no.10 is the sensor which locates near high pressure fuel pump.

no.21 is the thermo which locates under intake manifold.

I wonder if this no.21 is working.

Here's another one.
you can image the flow.

no.4 on this pic shows no.6 on the previous pic.

no.12 on this pic shows no.21(not exactly but including unit no.21) on the previous pic.

Interesting...so maybe the sensor is working properly and the high temperature is a true reading. I'll ask the technician and shop foreman what they think about this - thanks!

If anyone else has experience with this issue, please chime in.

My GTI is going back to the stealership tomorrow morning. Does anyone have any additional input before I take it back? Thanks so much!

I had this a very similar fault on my Mk5. The fans seldom went on after startup, but were on after strenuous maneuvering to my snow/ice-mountain covered parking spot. After I've had the sensor replaced, the fans are mostly off.

There are two temperature sensors for the coolant, like daigo said above.
I've also had problems with the fans working continuously when the dash was indicating 110 celsius degrees (almost on the red area of the gauge).

The guys from the workshop had replaced the wiring for these sensors and that solved the issue for me. The note they written in my papers was "doubled wiring for G62 and G83 temperature sensors", nothing mentioned about replacing any sensor.

I had 25.000 km since the repair and no problems (yet).

Good luck repairing your car!

Does anyone have a part number or link for these two sensors? My friends GTI just threw the cooling code and we thing it's that.

With the two temperature sensors, does anyone know which one provides the temperature reading to the ECU? I think my car is missing etc when cold until it reaches operating temp and the thermostat opens up and it sorts it self out.

enjoyincubus365 said:

Does anyone have a part number or link for these two sensors? My friends GTI just threw the cooling code and we thing it's that.

Click to expand...

You'll need to go to the dealer, but here's the writeup I did on it: http://golfmkv.com/forums/showthread.php?p=3271938#post3271938

Hi
my first post here! Hello!

Can anyone tell me what each of these sensors does?
Which one feeds the dash & which one the ECU? Which one the air con fan controller (if it has one).

My air con fans run all the time and I think one of these is to blame.
With eco selected the fans are off.
The dash temp indication seems to be working fine.
The internal blowers work ok.
When I select the air con on, the small engine fan runs immediately and loudly even if the car is still cold and the temp is still in the blue area (it comes on within 15 secs of starting the car from cold in the morning).
The large fan runs when the car gets too hot (i.e. in standing traffic) so that seems ok - its just the air con fan that seems to come on too early.
VW seem to think this is normal but it can't be IMHO.
Many thanks

According to the dealer machanic, ECU are monitoring the temperature gap between no.10 and no.21. By monitoring the value substracting these two sensors, to control the fan activation and speed.

No.10 shown on above pic is connected to the dash and ECU, and it is the main sensor to watch coolant outlet temperature. If you have VCDS, you can monitor the value of both sensors.

This is what I heard from dealer mechanic, that the fans are controlled by the gap substracted value of the 2 temp sensors.

engine outlet temp value - radiator outlet temp value = ECU decides which fan(s) and speed