[Clive Roberts]

I recently towed a heavy trailer, and the oil temp (selected on its display page) rose well over 100c, reducing as we drove downhill, increasing uphill. I thought the cooling fans didn't come on, at-all, even after stopping. So I thought there was a problem, probably electrical, or a sensor.

Next day I drove (without a trailer) for a short distance. The temp (dial) gauge didn't even reach its usual cruising 90C. After shutting down, the cooling fans were running.

Now I'm confused. Is there a problem or not?

 

[Crasher]

The colant gauge should read 90 at a real 77 and will still read 90 as a real 116 so if it does not go to 90 and stay there, it is over cooling. The ECU may have been performing a DPF regen.

 

[Clive Roberts]

Crasher.

I had to look up the 'DPF regen', as I had never heard of it. I think you are absolutely right. The car was getting rid of deposits. Many thanks indeed.

My next task is having to work out the download on the trailer ball. My Passat notes state that it must be no more than 90 Kg. Thinking cap on!