[tecas]

you only need to unlock it if you want to read via obd but to do that you will have to take the ecu out of the car and k-tag it on the bench unlock it and reinstall,

or as gezame says just writhe the correct file with the correct tool

Hi and thanks for the reply.  So now I will look into getting a valid 9971 FRF file for my ECU  03L 907 425 C.  Then as I understand you both mention, I can do a straight firmware overwrite from 9982 using ODIS-E and not have to unlock first.  If I am wrong about that, please do let me know.  

Still unsure on what the unlock does, I understand it will allow read via obd but doesn't ODIS-E offline need to read before it writes the new FRF file anyway?

Any other tips would be appreciated as I am still learning the basics.  Thanks.