[Koa]

Originally Posted by kch

To clarify what @Koa said:

1) Your OFT is "married" to the car whenever you flash a tune.
2) The OFT can clear CELs
3) However, to prevent the CEL from coming back, you must flash an OFT tune that specifically disables that CEL code.
4) To unmarry your OFT, you have to flash back to stock.

So I would actually disagree with @Koa and say that, for a long term solution, your answers are yes and yes.

Edit: If you have a CEL from an O2 sensor issue, it means you have a catless header, yes? If that's the case, you should really get a tune anyways, either through OFT or ECUtek.

You don't need to clarify anything but since you did, I applaud your contributions to solving homeboy's problem- it stands that one doesn't need to marry to the car to access and use OFT's diagnostic functions. I didn't make an assumption greater than the one presented by the OP.