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Michael, Ford Senior Master Technician
Category: Ford
Satisfied Customers: 275
Experience:  Ford Senior Master Tech & ASE Master w/14 yrs exp. Served on Ford's Tech Review Panel
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What does O2 sensor heater circuit malfunction (bank 1 Sensor 2) mean

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What does O2 sensor heater circuit malfunction (bank 1 Sensor 2) mean? How do I fix it ?
Customer what year and model is your vehicle? Which engine do you have?


Thank you,


Customer: replied 8 years ago.
1998 F-150 4.6
Customer each of the heated oxygen sensors, there are four, have a heater circuit. This heats the sensors up on start ups so they begin to operate properly. The all of the sensors share the same power circuit. The engine computer, also known as the PCM, grounds the circuit to activate the heaters. The PCM senses the ground side of this circuit, if the PCM does not see battery voltage on this circuit passing through the oxygen sensor it sets the code you have.


Since all of the sensors share a power circuit and you only are getting one code I believe the power circuit is most likely ok. Either there is a problem with the sensor itself or the ground circuit.


The proper way to test this circuit is to find the sensor. It is on the passenger's side after the catalytic converter. Closest to the rear of the truck. There are two sensors on each side. Disconnect the connector and use a volt meter to check for battery voltage on the red wire. If that is ok, then check the resistance of the white/black wire between the sensor connector and the engine computer. If that is ok, you will need a new sensor.


95% of the time this code is caused by a bad sensor.


Hope this helps, if you have any further questions do not hesitate to ask.



Michael and 5 other Ford Specialists are ready to help you
Customer: replied 8 years ago.

How can I tell what o2 sensor is the bad one ?? There are 4, am I right ? I changed one maybe 4 or 5 years ago. What does bank 1 and bank 2 mean ?