ryushe

Hi guys,

I've been getting the 'Increased Emissions' warning and decreased mpg lately on my 2004 E61 530D, and after some online searching came up with the most likely culprit in my case being the EGR and/or main thermostat.
So yesterday I did a test run with the hidden OBD menu showing actual coolant temp, and I'd like to know your opinion based on the results below. Outside ambient temperature was around 8-10 celsius.

When starting the car it showed around 33 C.
After 15 minutes of driving in normal city traffic, I was up to about 60 C.
Decided to get on the motorway and push it there for a bit, got the car to top out at 89 C, but it swung as low as 72 C.

Now I understand the car is supposed to run around 92 C if all is in order. I also understand that a thermostat (or both) should not have these kind of temperature swings. Am
I correct in assuming then that the temp swings I'm seeing is indeed due to faulty thermostat, bypassing the fact if this may solve my Increased Emissions problem or not?

If so, I'm ok with replacing them, but I'd like to know from those that have done so if all you replaced was the thermostats, or were there other items needed/recommended as well, such as as seals? Anything else I should be looking at while I have parts off?
And if someone could confirm the part numbers I have found are indeed the correct ones for my particular car, that would be great.

Main Thermostat: 11517805811
EGR Thermostat: 11717787870

Thanks much!