Temp troubleshooting

[Henn28]

Changed my coolant level sensor and now the coolant wont get hotter than 99 deg. Can’t imagine how these could be related, but a very BMW-like coincidence at any rate.

Any thought on troubleshooting this? Basically the car warms up, a little slowly perhaps, but gets to 99 degrees and hold it there, rock solid in fact. My experience with the OE 105 tstat (which is in the car) is that the temp will vary say, -10 degrees to +5 degrees from 105c/221F. Current my m62 is hardwired at 99 deg after it warms up. The oil temp is slightly low too…3 or 4 degrees or so.

The radiator outlet temp does vary significantly still under load, so seemingly the tstat is still working at some level. My foxwell indicates that MAP cooling is not active either.

Tstat failing or maybe a heater valve failure? My uneducated thoughts are that the heater valve has failed open, since it is 22 yers old, while the tstat is only 3 years old. Wouldn’t I feel a failed heater valve at the vents thou…hotter air?

I wish it would have gotten stuck at 90 deg so I could see if that triggers an SES light. I have a 90 deg map tstat I want to install, but don’t want to deal with a possible SES light so I’ve been procrastinating. Maybe I’ll pop it in along with a new heater valve.