Hello all,

What temperature is your V8 (545 and 550) running at when warm? I just changed the thermostat on my 545 and now it's stable at 102-105?C when warm, is that normal? Seems pretty high to me, should I be worried?


You can check your coolant temp from the OBD by doing the following:

1) Turn ignition key to position 1 (Radio)
2) Press and hold Trip button until 01.__ appears.
3) The car’s chassis number will soon appear below this – add the last five digits together, and remember this total for later on.
4) Press and hold Trip button to get 01.__ again, and then keep pressing the Trip button repeatedly until menu “19 Lock On” appears
5) As soon as 00 appears below it, immediately keep pressing the Trip button until this figure reads the same as the total number of the last five digits of the chassis number which were added together previously
6) Wait momentarily until menu 01.__ appears, and then press the Trip to get menu 07.__, and the temp. will appear.
If the car is started from this menu, you will get a continuous temp. read-out until the ignition is switched off again.

The above instructions are from this post, worked like a charm.

I'll check on the way home today :)

Wish there was a temp gauge...

Yes, me too, but the procedure above at least gives you a digital temp gauge until you turn the engine off, then you have to re-enter the combination again...

Ok. I got 102?C on the way home.

Thanks! I know the statistical basis is not very strong but from that I'm going to conclude that our cars operate at normal temperature!

I will sleep better knowing this, thanks again!

Hehe, no problem. I just wish I didn't have to enter the code EVERY time I start the car if I want to check something.

Will that procedure work for an 09 535?

98.6?

Kidding aside, all this is computer controlled. Why mess with it?

Had thermostat replaced on my 545 couple weeks ago because of the "Increased emissions" error. I looked at the new part and it had etching on the edge showing operating temperature - 105C. That device has no "brain". It opens itself once temperature reaches operating. In the cases when you get lead foot on the gas pedal and DME detects increased power with low speeds it turns on power of the heating element in the thermostat and make it open forcefully with speed increasing heating element turns off and back to normal mode