I was getting a check engine light with code P2181 and I read that the possible culprit were the temp sensors. I replaced a 2-pin gray sensor on the rear of the engine block but also bought a 4-pin green sensor that was also listed for my 2007 A4 Cabriolet. I have looked all over and do not see it anywhere. Previous models have it at the lower radiator outlet/inlet but mine is blocked off there with no sensor. Does my car use this one or is it in some other location? Thanks.