Thank You for answering me!

Question

Why would my Temp gauge stays in the middle if the thermostat is bad?

Answer 1

For the Wrangler and when a P0128 sets, this all based on predicted time that is set in the vehicles PCM ( computer system) This is all in respect of time , there is a predicted temperature start up and the base of what the engine coolant temperature sensor should be. If the base falls out of the calibrated time you set this code. This is known as the target value and the predicted value, Most of the fix for a P0128 is replace the thermostat,