How to fix P2181 Cooling System Performance - Coolant Temperature Sensor (lower rad hose)
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).
For this procedure you’ll need to drain some of the radiator fluid (I’ll show you how to do this efficiently and effectively)
I replaced both the lower and the upper sensor I’ll have that How-To below.
How-To for the upper sensor:
Estimated Time: 1 hour
- Torx T-25
- flatblade screwdriver
- Drain pan
- Temperature sensor (I used Beck Arnley 158-0784)
You’ll be working from the bottom of the car so safely jack up the front end of the car. Open the hood so you have some light beaming down.
You need to remove the skid plate or under car shield, whatever you call it.
There’s 4 T-25 screws on each side of the plate.
Once all 8 are removed the cover will just slide out away from the front of the car.
The sensor is located under the vehicle where the picture is circled.
Next, remove the lower rad hose with pliers or vice grips to move the clampThen, be sure to have a bucket underneath the hose to catch coolant. Then pull off the hose with your hands and clamp the hose with vice grips.
Now your ready to remove the sensor. Using a flat blade screwdriver gently pry the electrical connector until you hear a click noise. Then pull the connector off and pull the sensor out.
Then install the new sensor. Ensure you have a new o-ring installed and the old one is removed out of the inside of the assembly.
I found I had to push the new sensor into the assembly quite hard in order to seat it.
Then using a new c-clip push that in like so,
Then, connect the lower radiator hose and position the clamp back where it was.
I cleaned the surrounding area with a rag.
Now your ready to refill the coolant back into the system. Using a funnel and some rags, dump the remaining coolant slowly into the coolant reservoir.
I filled it all the way up to the very top of the reservoir and started the car. The fluid was immediately “burped” back into the system. Then I added the remaining fluid.
Check for leaks and ensure your coolant levels are correct (Top up as necessary).