you will need an obd2 to obd1 harness, quite a few people offer this, i believe skunk 2, hasport and prolly hondata offer it, id get it through a big name company so that it is more likely to be quality stuff if i were you. unless you are getting a steal on the a4, i would look into ordering a jdm obd1 h22a, much less hassle, and you can get it for cheaper most likely.