Right after I hit 50k in July, my check engine light came on. Per my mechanic, it was throwing the code P2181 - Malfunction in the Coolant System. They recommended changing the coolant temp sensor and thermostat. Changed both, check engine light came on two days later. The code was reset 3 times, so then we decided to replace the water pump and timing belt. Went three days, and then the code came back on. It has been re-set several more times, but the light keeps coming on w/the same code, P2181. I checked w/the dealership and they couldn’t offer me any other solutions. I’ve been driving with the light on for months now. Since the light is always on, I’m never going to know if something else goes wrong until it’s too late. I have a co-worker w/a 2004 Jetta that is having the same issues. Please help!
I would give the sensor another shoot. Is it the blue or green one that you now have. VW has had some problems with a batch (If I remember correctly the blue ones) of coolant sensors. You may also need to clean the contacts to the sensor.