The reason why retrofit (aftermaket) radios blow our scan tools is the O/Eq radios on VAG vehicles has a diagnotic port and on the retrofit radios do not but alas they all use the ISO plug, so the pin that VAG has allecated to radio for diagnostic purposes is the same as the electric aerial sensor wire on retrofit, Anyway if your interested Advanced Diagnostic do a tester for this (AD34 I think) for testing the state on the Diagnostic port to see if it is safe to fit your scan tools