DVDBob

I've got an '05 TT that has been running great. Took it in about 6 months ago due to a coolant leak. Shop fixed the leak, drained and refilled with G12. 2 days after the fix the CEL popped up and took it back. I scanned it with my cheapy OBD tool and pulled a P2181. Shop claimed it was the Coolant Temp Sensor so they replaced. Now, 6 months later, CEL pops up again and I'm noticing gauge fluctuates between 1/2 and just under 1/2. Code is same P2181.

Found the 49C trick somewhere and noticed the temps fluctuate between 78 and 81 celsius for the first 20 minutes or so of driving, then sticks at 81/82 (which I take to be normal).

From all the old threads I read, it could either be the CTS again or possibly the thermostat. Before taking it to the shop, I was going to replace the CTS again as I know these fail often, but if not the CTS, it appears to be a stuck open thermostat.

As the thermostat doesn't seem to be plugged into anything I was wondering if a bad thermostat would cause a CEL?

Thanks in advance.

03_AR_CO

A scan with the Ross-Tech cable and software would be more helpful in diagnosis, as well as getting a meaningful response from other forum members. You could look here for some of what to look for in the meantime: 18613/P2181/008577 - Ross-Tech Wiki