PO151 code

[Blade Guy]

A friend has an '18 softail slim. Put a set of Rinehart slip-ons on and within a couple weeks set the check engine light with the PO151 code (rear O2 sensor low/engine lean). The dealer told him he needed the Pro Street Tuner so he did that with the same result and then they said he needed a high flow air cleaner. I told him that would really lean it out. And it did. Are these EPA compliant Pro Street Tuners that limited that the lean condition can't be tuned out or is the dealer limited as what they can or can't do to cure a lean condition? Would the best course of action be an aftermarket tuner dialed in by someone that knows how to do a proper tune?

[rigidthumper]

If you want to verify where the issue is, clear the codes, reinstall the stock mufflers, and ride. If the code returns while running the stock mufflers & hi flow AC, check the wiring/sensor. If the code never returns (give it ~ the same miles it took to show up the first time), go back to the RH mufflers-if the code comes back after swapping the slip-ons, then yes, the SE tuner isn't able to adequately adjust for them. SE Street tuner is limited to +/-4% in the closed loop area of the map, and +/-10% in the open loop area. If you have a set of the cables, you could use the SEST to record data and see what was happening.