I have a 2000 Expedition and installed a low temp thermostat a couple of weeks ago. The other day the service engine light came on. I had the code checked an it was "P0125 -Insufficient Coolant Temperature To Enter Closed Loop" what does this mean how can I remedy it and is a result of me installing the low temp thermostat ?

 

Welcome to the forum.
Yes, but dropping the engine temp, it is not getting warm enough to run efficiently. The PCM doesn't go into closed loop until it reaches a predetermined temp.
Todays engines are designed to run at least 195 deg. to get propers ring seal and lower emmisions.
Put the stock 195 thermostat back in it. Your engine will last longer.
Jimmy

 

Thanks for the information, I put the old one back in.

 

I put back in the factory thermostat and the service engine light is still on. Is there another problem, when I had the code read it only listed one trouble code or do I have to reset the computer somehow?

 

It will eventially reset after a certain number of drive cycles with no codes being given.
If you can get it read for free, most readers will reset the light for you. Or, you can unhook the battery for about 15 min.

 

Thanks for the info.