Can this be solved by a home mechanic or is this a dealership fix
Being a skilled mechanic you would have already dove in using a meter and scan tool. If you feel confident in tackling the job, go for it. Otherwise a shop would be the direction to go. Only you know your own skill level.
Code P0126 – Insufficient Coolant Temperature
P0126 Description
The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the Engine Control Module (ECM). The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.
Possible Causes
- Low engine coolant level
- Leaking or stuck open thermostat
- Faulty Engine Coolant Temperature (ECT) sensor
- Engine Coolant Temperature (ECT) sensor harness is open or shorted
- Engine Coolant Temperature (ECT) sensor electrical circuit poor connection