[tardboi]

Well it's back today. Coolant -128c. No power. Same codes as before. 3 invalid signals + thermostat stuck open. Also code about reducing power.

[Bmwman325]

Originally Posted by tardboi

Well it's back today. Coolant -128c. No power. Same codes as before. 3 invalid signals + thermostat stuck open. Also code about reducing power.

My experience is when a sensor is giving you a crazy negative reading, the sensor is likely dead or the wire going to it is damaged. Track down where the sensor is. If its cheap and easy to replace start there. That wacky -128 is probably making the DME bug out. Also check your fuses, find what fuse runs the coolant temp sensor.

[Eschmacher]

Originally Posted by tardboi

Well it's back today. Coolant -128c. No power. Same codes as before. 3 invalid signals + thermostat stuck open. Also code about reducing power.

Checking back in, did you get this sorted?

[tardboi]

Yes I think I edited it on to the OP. It was the transmission heat exchanger thermostat.

[rugbyfool89]

Do you have a part number for the transmission heat exchanger thermostat? I'm having similar issues...

[rugbyfool89]

Originally Posted by tardboi

Yes I think I edited it on to the OP. It was the transmission heat exchanger thermostat.

Do you have a part number for the transmission heat exchanger thermostat that was replaced? I'm having similar issues.

[tardboi]

Originally Posted by rugbyfool89

Do you have a part number for the transmission heat exchanger thermostat that was replaced? I'm having similar issues.

17217600550
(Unfortunately the thermostat alone cant be replaced)

During repair these broke:
17128570061
11537793373


Did you check the hidden menu for coolant temp? There is a extended warranty on one of the F30 thermostats; I dont think this is the one though.