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I have an OEM P0054 code on an 04 Ford Freestar. Now assuming the wiring is OK and the sensor tests bad, after replacing the sensor what needs to be done to the computer to set things right? I mean get rid of check engine light and HO2S heater learn reset. Are those necessary steps.
The P0054 is heater resistance bank 1 sensor 2. I take that the code implies the sensor is still working just not heating, is this correct?
Thank you in advance for any replies.
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You just need to clear the codes with a code reader/scan tool.. No code reader? Disconnect the battery for awhile (at least 10 minutes) and it does same thing. As long as there aren’t other things like radio code/alarm issues to think about, go for it.
You didn’t mention if you need to run the monitors to pass an OBD2 inspection, but if you do, you’d need a code reader to know when those monitors have run. Fords also seem take a lot of driving to run monitors for inspection.
The accuracy of a O2 sensor is low until it reaches operating temperature in the exhaust system, and the heating element speeds the process up to maintain fuel efficiency and reduce emissions (i.e. reach closed-loop operation).
The P0054 error code means there is a fault in the heater circuit for the O2 sensor, which can be due to an open/dead heating element, poor connection, no power to the heating element, etc. I would test the sensor before spending the money on a new sensor. Measure the resistance of the heater element with a multimeter to determine if the heating element is faulty. A good element will have a low resistance (e.g. 100 Ohms or less), and a faulty element will have a very high resistance (e.g. MOhms or infinite). Also, check the voltage to the heating element at the connection to verify the heating element is receiving power. I think ETCG has a video on this topic.
+1 Fopeano’s response on resetting the system. You can borrow an OBDII tool from most auto parts stores.
+1 Fopeano’s post on resetting. If you have radio or alarm memory that you don’t want cleared by pulling the battery cable off, you can also clear the codes by identifying and pulling the fuse for the computer and reinstalling it after 10 minutes or so. This, of course, requires that the computer be on a different circuit from the radio and alarm, though. LOL.
+1 on testing the sensor before replacing. I advised this on your other thread too. Please test it before finding out you bought one unnecessarily…they usually cannot be returned.
Thank you much for replies.
So I figured out my problem. After doing a resistance test on the sensor, it was good. I followed the 4 wire harness from the plug-in to the computer and found it to be completely severed. Being the genius that I am concluded that was my problem.
I replaced the section of wire, now giving power and receiving signals from the sensor.
This is where I am lost. What do I need to do to get the computer back in sync with the sensor and remove the check engine light. I have heard just disconnect the battery for extended period, but I have also heard with Ford learned memory, systems don’t go back to proper fuel/oxygen ratio.
And again, thank you for your time and knowledge.
The two codes I received were P0054 and P2270.The best way to clear the codes is with a scan tool. Without that, the methods above will work. It will not take too long for the computer to re-learn any data that was lost. The computer has to do the same re-learning whenever the battery cable is removed for more than a few minutes for whatever reason. It won’t hurt anything.
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