Noticed on vcds the engine temp never goes above 80.2 and if sat iddling drops to 77 ish.

 

temp gauge on dash reads 90 and seems to stay there. Normally when I’ve had a stat go the temp drops as you drive faster.

 

im leaning towards a sensor fault?

The gauge on the dash lies... It's designed to read 90'c over a wide range of temperatures to avoid drivers getting worried that the temp is changing

 

 If the water temperature never hits 90'c, then the thermostat has probably failed. I had mine done recently: https://www.briskoda.net/forums/topic/327055-20-tdi-cr-temperature/?do=findComment&comment=5331457

Edited 2 March, 20206 yr by langers2k

ill try logging it. I just thought if the stat was bad the temp would drop at speed, had this before when stat was stuck open. can you have a partially open stat?

Mine was fine at a-road/motorway speeds but if I stopped in traffic in cold weather, the gauge would start to drop. I don't think it'll move off 90'c until the temp drops below about 75'c.

 

I've no idea if it failed fully open or partially open as the garage replaced it for me. I'd expect it's possible for it to fail in any position.

Get a new, genuine thermostat and you will see that temp improve although you will still see them temp drop off a bit at idle, especially in cold weather if your running the heaters.

 

As above, the indicator on the dash isn't very useful

How do the temp sensors normally fail? Do they read totally wrong?

They tend to drift to higher resistance (lower temp than reality indicated) or leak coolant into themselves and short out.