Thermostat or Sendor or something else problem?
Here the story. Hopefully somebody on here will be able to give it a happy ending.
My 04 plate 156 1.8 is running ok, but the MPG has dropped from a very good 40+ to low 20's. At the same time the following is happening to my temperature readings. In normal driving the needle doesn't budge, it sticks to 50 during a 40 minutes drive. The only time it moves is when I'm standing static at lights for 5 or 6 minutes and it will slowly, slowly creeps up to 90. As soon as I pull away it will plummet back down to 50 within 200/300 meters. Ok, so I've been on this forum and everybody is suggesting the Thermostat so I got a new one and changed it. This has made no difference. Next I change the Thermostat Sendor again this has made no difference. I'm not getting any codes from the OBD2 reader. So does anybody have any suggestion that will give me the happy ending that I want.
Thanks in advance for any suggestion.