Problem with OBD following aftermarket radio install
 

Hi all, I have a 2003 Audi TT Quattro, and I replaced the radio with an Apple CarPlay unit months ago. It’s smog check time here in California, and my mechanic can’t connect to the OBD for the initial reading. Well he can connect but the machine he’s using can’t “talk” with the unit. He says it’s a wire (the k line?) that was connected wrong during the install, and needs the OEM radio (which I don’t have). First, has anyone heard of this? Second, any workarounds or do I have to buy the original radio and code it and all this? Thank you for your help in advance if anyone knows what’s going on!