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O2 sensor code

Started by Blade Guy, May 23, 2019, 03:03:35 PM

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Blade Guy

...on an 18 Heritage w a SE Stage IV. Last year kept throwing a PO154 code (rear O2 sensor). Another dealer said the box for wide band sensors wasn't checked, hence the code. Still throwing that code occasionally, no difference in the way it runs. Accidentally reset the last code it threw-dealer said it has to have the code present in order to diagnose. I did verify that the auto tune unit is grounded on the clean ground. Any ideas? Bad O2 sensor?

Blade Guy

Thought I would put closure to this post. Finally after 3 dealers and a lot of ridiculous guesses on 2 dealers part I'm confident this issue has been finally put to bed. The reason I kept getting the O2 sensor code (P0154) was the Auto Tune unit which connects to the wideband O2 sensors was not grounded properly. To this forums credit that issue was discussed in previous posts about this problem. Unfortunately I didn't understand what was being said. A couple months ago American Iron magazine had a tech question about this very issue. So I pulled up the instructions on line for this part and finally understood what a "clean ground and dirty ground " are and where they're located. The Auto Tune needs to be connected to the clean ground, mine was except the lug was touching the frame making it a dirty ground. That sets a check engine light because the O2 sensors are now getting electronic "noise". Also the Auto Tune module itself was put on top the battery and was banging off the negative terminal. Everything was replaced (correctly) under warranty and I'm finally good to go.