Hey all I know this is my first post and I've done my reading but I'm still unsure if this is possible without problems arising. Looking for answers about straight up flashing over an existing Apr tune on my m box 01 s4. It seems reading the file causes problems, just not sure if writing over it causes the same problems. I have my blue vag cable and have used the nefmoto software to log and check dtc's so no problems connecting, still waiting on my galleto cable to arrive(just in case of a brick). I've seen that reading and copying the epprom memory with argdub's tool is a good idea in case of a failed write, also the charger to keep battery levels consistent. It just seems that every post on here that talks about an apr flash seems to end in bricking an ecu or people that are unsure if it can be done. If anyone can give me some solid answers it would be greatly appreciated. TIA

This is what I believe, but in way way can I be trusted here.

If its a APR soldered chip you need to remove it and solder in a stock chip to get back to a stock tune.

If its a APR flash, you need to save the EEPROM with the tool mentioned above. And flash the stock tune in BOOTMODE to write
over the APR tune.

Im not sure if you can READ the APR tune in bootmode to save it as a backup if you wanted to re-use it.

This is all what "I THINK".
You need to get this confirmed or rejected.

I know this is old, but is this true for MED9.X ecus also? Could MPPS write over the APR tune with out having to resort to boot mode?

Not sure its possible to write full flash via OBD.
Agree, BDM is the best way.