A friend asked me to pull codes off his 99 ranger. Has a 3.0L V6 Flexfuel engine.

P0125 - Insuff Coolant Temperature for Closed Loop Fuel Control
P0153 - Oxy Sensor Circuit Slow Response (bank2-Sensor1)

I very quickly diagnosed the P0125 as a bad tstat. Just a guess, but its a $10 part so he was okay with giving that a shot. Not sure on the O2 sensor one. Can the engine not getting to temp cause the O2 sensor to not heat up properly?

 

Slow response from o2 sensor is usually a bad sensor .

 

Replace the thermostat first, then re-check.