How to fix P2181 Cooling System Performance - Coolant Temperature Sensor (engine bay)
Today I’m fixing error code P2181 Cooling System Performance engine code. There are a few causes of this code such as:
- Failing Thermostat
- Cooling fan
- Coolant Temp Sensor
I managed to solve it by replacing the Temp sensor. There are 2 temp sensors on the 2.5L Mark V Jetta, 1 located in the upper engine bay and 1 located on the bottom of the rad (beside the lower radiator hose).
I replaced both the upper sensor and the lower sensor I’ll have that How-To below.
How-To for the lower sensor:
Estimated Time: approx 35 minutes
- Vice grips/pliers
- Screwdriver Torx T-25 (I think)
- Temperature Sensor (I used Beck Arnley 158-0784)
Remove the engine cover, I’ve previously made a How-To that shows how to do this. Follow Step 1.
Next, in order to physically get to the temp sensor you’ll need to remove the intake pipe. Use pliers to squeeze the clamp.
remove these 2 hoses by squeezing them by hand:
Now with the hose removed your ready to access the sensor.
Next, you will need to located the sensor itself. It’s located underneath-beside the oil fill cap.
Next, remove the electrical harness. Note: I broke my clip off by accident, to avoid this gently pry a flat blade screwdriver into the notch and you will hear a click sound.
Next, using pliers or vice grips in a twist motion pull out the sensor (it is not threaded in)
Finally, be sure to remove the old O-ring if it did not come out on the sensor. Using our new sensor, O-ring and C-clip, we are ready to install.
With the sensor pushed in, be sure the c-clip is properly positioned above the sensor like so
Now follow the instructions backwards for re-assemble.