P0125 Toyota - corolla ce

Question

The check engine light came on Friday after drive from McKinney,TX to Shreveport, LA diagnosed problem numbers of p0171 and p0125 I have a 1999 Toyota Corolla CE all fuel levels are fine, coolant, oil, power steering etc.

Answer 1

P0125 Insufficient coolant operation for closed loop operation

P0171 Fuel trim lean Bank 1

P0125 has a variety of code for your vehicles , this is per Toyota. it can relate to the coolant temperature sensor (ETC) where the thermostat is not operating as intended. or the 02 sensor is not operating as intended. Where the engine temperature is not at closed loop. If there is a exhaust leak prior to the front 02 sensor this can cause P0125 and P0171. A vacuum leak can also set these two code or just a failing  front 02 sensor. These code condition is more of a lean running condition affecting the perfromance of the front 02 sensor, rather than being a coolant temperature sensor.