tom_il

I have those moving lines but : they stop before the enigine reaches 90°C which is the normal operating temp. At 80°C they don't move at all any more. So don't just rely on them. Also this is just water temp, the oil temp which is alot more important is far from its normal operating temp.

Also these lines are different for different engine types. On the 535d they are for example different then on a 525d or 530d.. On petrol they are a again different.

So check the engine temp on the secret menu and make sure it reaches 90°C.
Forget those lines, they are better then nothing but that is about it, they arn't even there anymore on the E60/61 LCI models.

And Redtwin is right, the thermostat is a pure mechanical device. There no electrical connection to it , so error will be generated. You would be surprised how many E60/61 are driving around with faulty thermostats (mainly the EGR one) without the owner knowing. And the dealer can't check it either without driving around with the car. As a result these engine consume more then they should, have DPF problems since they don't generate, and shorter live since they run to cold.

F-Tar

In 530i the thermostat is electric... So diesel engines seem´s to be different on that part.

I see, then they're not that accurate after all.. Yeah, i will try to connect the car once again to take a look what the coolant temp is when the engine has reached full temp.

I also think it has to me mechanism related that the lines won't move at all, ever. No, this issue is no big deal as long as the engine get to it's normal operating temp. I have to check that out.

Maybe bmw relalized that those lines is in most cases useless. Why not put an true temp guage instead. It cannot even be coded but that would have been awesome.

tom_il

No need to connect the car. You can open the secret menu between the gauges where you folow the engine temp when driving the car.