bad gas mileage because of bad thermostat?

[DiamondStarMotors]

I bought a OBD-II to usb cord and software. MY dad and I go out for a drive to see why my mileage has been terrible.
As soon as the program connect to the ECM. I got a stored code, P1108 or something containing those numbers, I can't remember at the moment.
We soon go to a different statistics page where it the says the Engine is at -40 degrees F... Yes, negative... and on another page the program was reading a normal operating temp around 200.

any advice?

 

[silvreclips]

Either a bad coolant temp sensor or the wiring to the sensor has a problem.

 

[91boostedgst]

First check wiring then replace sensor. When this sensor goes bad it send a signal to ecu that its -40 so there for ecu thinking its actually Cold out it thinks it needs more fuel to run.

Someone correct me if im wrong.

 

[reddragon1]

Check the wiring then go from there. But that's the reason the car gets bad gas milage. The ecu use the etc sensor to calculate the fuel trims at any given point so if it sees -40 it thinks you are still trying to warn up the car after blizzard .