SYMPTOMS: Engine temperature arrives very hard to 90C and does not maintain it at 90 degrees. The temperature will get down even to 40-50 degrees when driving out of town at high speed.
SOLUTION: Changing the EGR thermostat (it is 90% of cases). I recommend to go for OE BMW or BERH (the manufacturer for original EGR thermostat for OE BMW).
A good tutorial on how to change the EGR thermostat:
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