I’m back with some more high-mileage antics! My car threw a P2181 CEL for cooling system performance a few months ago. The temp gauge took a long time to reach 190 degrees and would dip below if I was on a downhill stretch. If you’re seeing a cooling system performance code or are having a hard time reaching normal operating temps, your thermostat may have failed.
Thermostats are designed to fail in the open position to prevent overheating but this also prevents the engine from reaching its optimal temperature. I live in California so the car didn’t really give me any problems but in colder climates, not reaching operating temp may be harder on the oil and in turn harder on your engine.
The 2.0T FSI’s thermostat is a very cheap part (under 50 dollars online) but it’s jammed in a hard to reach location. This is a job that I took to a mechanic. They can dispose of the coolant properly as well. If you wish to do this yourself, the thermostat itself is part number 06F121111F. I don’t know if it comes with any of the necessary o-rings so you may have to source them. I know ECS sells a kit with the associated bolts and o-rings so it may be easier to purchase it from them.