I have been struggling with persistently low coolant temp in my bone stock 2013 JCW with 160,000 miles.

I have a new thermostat - which helped to the tune of 25-30°. I'm vacuum bleeding and I'm confident that there is no air trapped. Resistor on the fan is good and it runs in both high and low speed.

I just can't get the coolant temp over 150 - 155°F. My Schwaben tool shows a code of "2947 - Coolant temp permanently stuck low".

Searching around - If the computer sees problematic temperatures or fan problems - it forces the fan to run at high. If that's my problem - How do I chase which parameters are out of range?

I'm thinking the computer is commanding the thermostat open. What do i look for to diagnose that?

All my continuity between the thermostat and fan and DME seems fine.

Thanks Guys

 

Firstly, what is your actual coolant temperature?
Get an infra red temp gun, and measure the temp on the metal on the end of the radiator tank. That is not exactly the same as the coolant, but not far off. If that is higher than the temp you are getting from the obd, then that would suggest that the temp sensor is faulty.

 

So -
My indicated temp (from the scan tool) and the actual temp of the coolant seemed to be tracking just fine.

I disconnected the "controlled" part of the thermostat and pulled both fan fuses, then cycled the coolant up to 230°f for a couple of cycles. ( I could only get it this warm when I was stopped - as soon as I started moving the temp dropped).

Does anyone know what temperature the "safety" thermostat opens at?

My running temperature is now in the 180° - 190° range (40°-60° ambient) and seems to be OK.

Thanks Guys!

 

Talked about here on the testing.

https://www.mini2.com/threads/r56-n1...7-code.374009/

A stuck open thermostat or slow to open thermostat will run cold. But i would recheck the connection and make sure the plugs sockets are good and tight.

 

To follow up on this -

I disconnected the "ECM Controlled" thermostat and pulled both fan fuses and ran the car until I saw 230° F on the scan tool on two separate heat cool cycles.

I could only get above about 210° when stopped - when I started driving, the coolant temp would immediately drop.

This seems to have purged some trapped air from the thermostat - everything seems to operate properly now with the thermostat reconnected and the fan fuses back in.. The engine warms up slower than my other cars, but I have heat within a couple of minutes, the fan seems to operate correctly and the "Thermostat stuck low" code hasn't returned.

Note - the original problem was after using the vacuum fill tool to fill the system, and using the bleeder screw on the thermostat at temperature multiple times.

Off topic - the BMW driving cycle to reset monitors (found on a search here) works a treat. Basically - three minutes parked from a cold start, four minutes at a steady 20-30 MPH without stopping, then 20 minutes at a steady 40-60 MPH without stopping. Even living in a rural area, I needed to head out at 9 PM to have a chance at the "not stopping" part. In any case, one monitor cleared in the low speed portion and the other two were set about 4 minutes into the 40-60 portion.

Thanks Guys!