Does an ECU need to be reprogrammed if putting a new one in your car?
 

I have a 2000 Audi A4 that may need an ECU. Called around to some junk yards and found the one I need "3BO 907 551 G". They said they had one out of a Passat that matched that part number. He said it may need to be reprogrammed. What all is involved in switching out the ECU? What would I need to do? If I used an ECU from an Audi would it have to be reprogrammed? Anyone have a spare used ECU that will work for me (as an alternative to the salvage yard one)?

Thanks! (BTW, runs runs real quiet now with new fuel pump, just still runs poorly).

It may need to be recoded for your car....
 

try car-part.com if you haven't already...

How would it be recoded? I have some requests on carparts as well.

A VAG tool can do it or ross tech's vag-com.... call the vendors on car parts it's the safest and
 

fastest way... I bought 2 ECU's that way. Reasonably cheap, too.

Do I have to VAG it if I get one from an Audi? Or do you have to VAG any of them, regardless ...
 

of car it came from? And will it run if I just put in it? Reason I ask that last question is that I would have to take it to shop to have them VAG it and I can't see paying them 1/2 labor to just install ECU.

If you get it from Audi they'll charge you an arm and a leg, but they'd probably put it in and make
 

sure it works. If you get it from an identical car to yours, you won't have to do anything except maybe clear any codes the used ECU might have. For everything else a VAG tool is a must. A tuner shop should be able to install it and recode it for you. You have to ask them for pricing. Or use the vag locator and find somebody willing to help in your area..

Thanks! I want to find one from a salvage yard that is just like mine so it is an easy swap...
 

Would it have to have all the same options: cold weather package, sport package, navigation (yeah, mine has factory C nav), etc.? Or just would it have to be a 2000 A4 Quattro 2.8 with tip?

I'd search the forum and read the FAQ, but IIRC ESP and transmission are the most important
 

parts.... There'll be only few A4s with NAV around and even less wrecked ones... :)

I STFA and couldn't find an answer, except re: a 1998, which just says put in new ECU and do...
 

throttle body adaption and you are done. I figure there has to be more than that!