IIRC the cooant temp sensor sends seperate signals to the ECU and the gauge on the dash. When my coolant temp stopped working on the dash, the engine was still running fine. Checking on the Climate Control unit or Vagcom, you could see that it was correctly showing the coolant temp.Mentor wrote:Coolant temp sensor seems to be working fine. I had a faulty one before and the water temp gauge was all over the place, sometimes reading 90 then 60 then 0. I'd have to agree with you that the fueling does seem to be off, but because of what remains the mystery.
So in summary, don't believe what the gauge is telling you! It may be correctly registering 90 on the gauge, but sending different readings to the ECU.