My 2007 V6 4.0L Mustang's emission light keeps coming on. The code reads coolant/thermostat. Before light was coming on, I had already replaced the thermostat, water pump and coolant sensor. Any ideas as to what is going on? Car runs fine, isn't losing coolant or overheating.

 

Hi. It'd help to have the exact code you've got. Probably a busted sensor, maybe a wiring issue of some sort, but it's also possible it's something else, the code will help point us.

Welcome to the forums!

 

What he said!