I have a Passat 2006/2.0T with an error code P2181 (coolant issues problems). The Temperature gauge seems to be ok, at idle, stays around 190-200, when I turn the AC the big fan comes ON, but the small fan (in the radiator) doesn't come up at all. The error code P2181 suggests that I may have a bad CTS, it is not that expensive, I can replace it. The car has 94,000 and the CTS never has been replaced. Could a bad CTS prevent the high temperature fan from coming ON? I have not tested the fan, but it seems to me like an easy taks just to replace the CTS. Any other ideas?