05 Ford Focus 2.3L engine getting a F0128 code on reader. Checked coolant level-good, rad. Fan works when it should. That leaves the thermostat, anybody out there done a remove n replace? Would appreciate any input.

- Leaking or stuck open thermostat
- Low engine coolant level
- Insufficient warm up time
- Faulty engine coolant temperature sensor
- Engine coolant temperature sensor harness is open or shorted
- Engine coolant temperature sensor circuit poor electrical connection

Make sure you only use a 50/50 mixture of G-05 antifreeze and distilled water. Change the coolant every 30,000 miles. Minerals in tap water may be responsible for the thermostat sticking.