Temperature gauge irregular: can it hurt the dpf?

[JGO]

Driving around in the city with all the traffic stops/starts and slow momentums my 2019 XF gets to temperature (on the digital gauge) and stays there, but within 10 minutes of dual carriageway or motorway speed the temperature dial drops down to the 'blue' on the dial and just hovers there. Also noticed the stop/start is not kicking in. How is one supposed to clear out the DPF if the temperature isn't correct.

Otherwise all things relative, car purring like the cat it is 👌

Any pointers really welcome, thanks.

[LairdScooby]

It does sound as if you have a weak thernostat there Jason but you are quite correct, DPF regeneration doesn't normally occur until the engine reaches a minimum temperature.

Often what works is manually selecting a lower gear to drive in and drive at motorway speeds in that gear so the revs are much higher than normal for the speed. This should also bring the engine temperature up a bit.

[JGO]

Ok thanks for that tip I’ll give it a go. Out of interest where would the temp sensor be situated? Wondering if I’ve dislodged something if it’s external to the main block etc 

[LairdScooby]

Not that familiar with the diesel engines but usually temp sensors are on the head, usually one or the other near the thermostat housing.

If you had dislodged something there's a fair chance the gauge wouldn't be working at all and you'd have error codes flashing at you on the instrument panel.