The car above car has 19K miles with no drivability problems. MIL is on, a scan shows the following codes P0125 Insufficient Temp for closed Loop and Pending Code P1133 A/F sensor Circuit response Bank 1/Sensor 1 . I am told that is a common code for a bad A/F sensor at Bank 1/ Sensor 1 and the A/F sensor should be replaced. Would like some input on this. Is there a way to check the A/F sensor like an O2 sensor with a DVOM? I checked the Heater voltage from the ECM with the A/F sensor unplugged, ignition on and engine off and read 9. 6 V, while V Batt was 12. 0. If a check on the sensor can't be done, it is a good bet the sensor is bad?