It has not been proven but since the normal operating pressures is about 1.0/1.2 bar or so, I'd feel better knowing the max pressure isn't 2.0 bar, basically at that pressure your system is boiling and you better be pulling over, your needle pegged into the red, etc.

If the system is venting you know the pressure is getting too high and you have other problems in the cooling system, I'd prefer the system let me know that at 1.4 bar instead of 2.

There's a reason that the E90 is back to 1.4 bar max venting pressure, and the E30 I think started at 2 bar but switched to 1.4 bar.

Long discussion about this on bimmerforums etc pertaining to E39 and E46, regardless, your cooling system should be maintained regularly but no negative effects of swapping to a 1.4 bar cap.

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