smog check message "cannot communicate with car"

[gabe107]

i went to smog my 1998 a4 and that came back, when pluging the car in it couldnt communicate, any ideas? knowledge or what part is bad thanks

[B5A4Kevin]

check the diagnostic fuse. it should be one of the micro/mini fuses and i believe it is 5 or 10 amp. fuse position 5 iirc. refer to the cover to be certain. i have seen a few tester cables get shorted out and pop that fuse causing no communication.

[gabe107]

thanks man ill give that a shot, and repost

[20vpower]

if thats fine, then check the fuse in the back of the radio, that blows and you cant access the obd port

[gabe107]

well that fuse is fine, along with the others, any other ideas?

[gabe107]

so i found out that if you have an aftermarket stereo in older audis it cannot communicate with the smog machine and you are exempt from that part haha

[20vpower]

exempt eh? from readiness codes and cels? explain more, i would assume they would make you fix it before they passed you.

[Kyle H]

Is your abs/brake light on?

If your module is bad it wont let you communicate.... you just need to unplug it if so.