Coolant temp sensor?
 

If anyone has experience with this problem, insight is appreciated.
I have a 2003 Mini Cooper s. I have a engine service light on. I've reset it. Cleared the code, changed the thermostat, flushed and filled... The light and code keep coming back. Any suggestions what to try next?
Code: P0128 Coolant Thermostat (coolant temperature below thermostat regulating temperature).

Hello David! What thermostat did you install?

Thermostat
 

Can't say I'm entirely sure. I ordered it, I think online, it was supposed to be oem. That I'm sure of. It was a few months ago. Do you think it's possible that it was not oem and that's what is causing the problem?

I have seen a few instances of this and when replaced with OEM or Genuine the issue went away, but it's hard to say if that is the reason for sure. It could be a faulty temp sensor, here. I'd recommend you check all connections/wires and go over the install to make sure you didn't miss plugging something back in. Check out these links for further options on possible issues. It could also possibly be a faulty part so check on the warranty information from the thermostat you purchased.


Check out these links here:
http://www.obd-codes.com/p0128
P0128 - Coolant Thermostat Malfunction - OBDII Engine Light Trouble Code | AutoCodes.com

Possible a stuck or bad thermostat new? Did you get a Genuine MINI version ?