SQ5 BiTDI Coolant Temperature Fluctuates


Registered User

I have an issue with my 2013 SQ5 where sometimes the coolant temperature only gets to around 75 Deg C on the dash and fluctuates a little either side of this. Sometimes it'll be rock steady at 90 which obviously is fine.

I've investigated a little with VCDS and it seems that the ECU is asking for the coolant temperature to be 75 Deg C sometimes. The 'coolant temperature at radiator outlet: specified' value is 75 or sometimes 90. When it's set at 75 and the coolant temperature creeps up to 76 or 77, you can see the map controlled thermostat F265 duty being increased to lower the coolant temperature, causing the small fluctuation. I can't find what affects this specified value.

Has anyone noticed this with their own BiTDI or could anyone suggest why the car would want to lower the coolant temperature like this?

Many thanks,