2007 Mustang 4.0L V6 Emission Light Question
The Emission light went on my 2007 Mustang 4.0L V6 earlier this week. I took it to AutoZone and got the error code read. OEM Number: P0128. The print out said it was either low coolant (which it isn't), a defective thermostat, or a defective Engine Coolant Temperature sensor. Is there any way to determine which of the two it is before replacing either?
Also, anyone else that's had this problem care to comment with advice on what you did to fix? Or if you took it in how much was it for a shop to do?
Any help is appreciated, thanks!