Possible causes
– Faulty O2 Sensor Heaters
– O2 Sensor Heaters harness is open or shorted
– O2 Sensor Heaters circuit poor electrical connection
– O2 Sensor Heaters harness is open or shorted
– O2 Sensor Heaters circuit poor electrical connection
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1127 FORD Description
The heated oxygen sensor (HO2S) monitor uses an exhaust temperature model to determine when the HO2S heaters are cycled ON. The test fails when the inferred exhaust temperature is below a minimum calibrated value.