2006 Ford Focus ZX3 P0128
The engine is a 2.0L Duratec and has 100K miles. I live in Phoenix, AZ. This is the third straight year this problem has happened...approximately 65K miles first time it happened. In October, when it cools off here, the check-engine light with the P0128 code comes on. That code indicates low coolant, bad thermostat and/or sensor. Coolant and temperature gauge are OK...the car runs fine. In March, when it starts warming up here, the check-engine light goes off. I haven't changed anything. Any ideas? Arnold
Change the thermostat with the proper temp. thermostat that Ford calls for.