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Thermostat Replacement – CE and loud aux fan issue fixed
So Saturday morning I woke up early and decided to change out my thermostat. The job took approximately one hour and was very straightforward.
Why did I change the thermostat? - My check engine light was on and indicated problems with the thermostat unit. The initial thermostat code also triggered additional cascading codes such as"engine running too lean" (due to improper engine temperature) etc. Changing the thermostat also seems to have cured the 100% auxiliary cooling fan issue for me.
Outside of your normal socket tools all I required was one quart of BMW OEM coolant from the stealership (To replace what I could not catch) and a flexible socket joint to get to the back bolt on the thermostat. After the job was completed I reset my check engine light and it has not come back since. If yours does come back on there are two other sensors in the cooling circuit that you can try replacing for cheap (Changing the other two sensors also is often a fix for the 100% auxiliary cooling fan issue).
What I would do differently next time? Next time I would drape the belts and other equipment below this thermostat removal point with shop towels. No matter how nice your catch bucket is if you do not drain the radiator ahead of time you are going to loose some fluid and it will get on the Belts. I rinsed mine with water and wet rags afterwards but I wish I didn't expose them to the spilled coolant in the first place.
Here's a great N62 engine thermostat change video for reference if you are thinking about doing this yourself: