This all started because I was trying to troubleshoot a cold start issue.  Car is a 2001 AWW 1.8T mk4, but I was using an 8N0906018L AWP TT file on a spare 06A903032DL ECU because its 4 motion swapped and there are some additional EVAP valves I had to install.

Anyways, that part doesn't really matter.  I adapted the immoblizer using the ID number from my cluster saved into the spare ECU with the TT file about 2 years ago.  It ran and started just fine for 2 years including my SAI delete and even passed emissions testing.

Now fast forward to this week.  I got a new turbo, so I was changing some things around in the flash to try out.  After the first download, the car would fire up and die immediately.  If I held down the accelerator it would get through and run perfectly.  I thought it could be from my SAI delete (pump and solenoid are removed) using MSLBAS and MSLUB, so I was trying some different things and flashing different files.  It still wouldn't start right.

So why is this post in the Immobilizer section?  Well, I finally decided to just put the old stock 06A903032DL file back on there.  Tried to fire it up, and the immobilizer light is on?  I took the ECU out and read the EEPROM and it doesn't match the original file I put on there, a bunch of stuff in the middle is different.  AND it says NEFMTO in the last 2 lines of the file.  Why the hell would that be in there?  Is there a bug in the Nefmoto flashing software that accidentally wrote to the EEPROM?

Anyways, my old APR tuned 06A903032DL ECU is back in the car and it runs perfectly again so it has to be a problem with this ECU's flash/EEPROM.

I attached the original and new EEPROM dumps, along with a screenshot of the hex showing the NEFMTO at the bottom.

I might just immo defeat it and try again, maybe the immo communication on the 06A903032DL is different from the 8N0906018L or something.  But why did the problem just start now after 2 successful years?

Thanks, that's good to know.  I'll try turning off the immobilizer and try again.