Hi, noob here.
Sorry to dig up an old thread but, I have had almost word for word the same problem as Daox.
I replaced my sisters 05 engine with a low mileage 07 from a local guy after a massive timing belt failure (the tensioner melted)
after doing some online research and trying almost everything else I took it to a dealer for a relearn, only to get the run around and a lot of bad customer service.
First time I took it in they just flashed the ecu after correcting me and telling me it was called a "pcm"
of course the engine light was flashing again not a block away from the dealer.
Second time I brought in a paper with instructions for the procedure. When they finally let me speak with their "master technician" the next day, he had not performed the relearn and informed me that the car needed a complete new wire harness for $2000 because I had broken off the little tabs on fuel injector pigtails and the loose connection was causing the error code, after pleading with him to please try the relearn anyway, he agreed and took the car back for 10 minutes then returned it with the light off.
I was cautiously optimistic and after test driving it around town for a bit I returned it to my sister only to be informed that it was back to its same antics after she refueled it.
I was at my wits end, I even tried replacing the injector pigtails with some from the wrecking yard that I carefully soldered in but, still no dice. I'm starting to think that the dealer just B.S.'d me and reset the ecu but, I can't afford to just shell out another $100 on that hunch. I would really appreciate any more advice you guys might have on this subject, or if anyone knows a way to hack the ecu or somehow disable the error code? it's an automatic so driving around without overdrive is a huge problem.