Ford Repair: o2 sensor, oxygen sensors, tool program

Question
QUESTION: I have a 1997 expedition w/5.4L I've got a PO141 downstream heated O2 sensor heater circuit fault(bank 1). My question is which of the 4 sensors is it indicating is bad. This is the fourth time in 7-8 years i've owned it, that this has occured. Which is considered bank 1 and bank 2. I would like to check it over before it goes back to the dealer for another repair. thanks.

ANSWER: The sensor in question is located after the catalytic converter on the passenger side. You are in luck, you should be able to tackle that one yourself. You will need to hit the sensor threads with a good soak of penetrating oil at least 30 minutes prior to removal, for ease. You will also need the specialty tool(s) available at all parts stores for around $15. Most even have a loaner tool program to get all your money back. Be sure and buy the OEM sensor, Universal sensors are way too much headache.

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QUESTION: OK. Ive changed the rear passinger o2 sensor with an OEM part. Do I have to take it somewhere to have the code cleared or can I diconnect the battery positive connection. And would that sensor have caused another error? thanks

Answer
No, no and no. After I answered this question, I knew I should have went ahead and told you this, so I apologize You have to complete the proper amount of drive cycles to clear the code. Deleting the code from the computer's memory can only make matters worse, especially if you have an emissions policy in your local area. Drive cycles can be best described by your local dealership. I usually complete them by trips on the highway, then my local mall, then back on the highway. However, you should also know that oxygen sensors become defective due to their operating conditions. You have at least one more sensor exposed to identical conditions in that same bank exhaust pipe.