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DIAGRAM 3: 2001 Heated O2 Sensor #1
This is the typical circuit diagram of the front oxygen sensor (HO2S 11) of the 2001 2.5L Ford Ranger and 2001 2.5L Mazda B2500.
The front O2 sensor (HO2S 11) is located before the catalytic converter on the exhaust pipe.
You can find the HO2S 11 heater element test here: How To Test The Front O2 Sensor Heater (1998-2001 2.5L Ford Ranger).
DIAGRAM 4: 2001 Heated O2 Sensor #2
This is the typical circuit diagram of the rear oxygen sensor (HO2S 12) of the 2001 2.5L Ford Ranger and 2001 2.5L Mazda B2500.
The rear O2 sensor (HO2S 12) is located after the catalytic converter on the exhaust pipe.
You can find the HO2S 12 heater element test here: Rear O2 Sensor Heater Test (1998-2001 2.5L Ford Ranger).
