Hi,
I'm hoping you can help. I have recently retrofitted Xenon lights to my A4. Had to replace J519 control module and have component protection removed. Since doing this I have no air con. VCDS shows HVAC 00898 implausible signal error which comes straight back after deleting. Have replaced sensor (just in case) and power to sensor ok but no signal/power to a/c compressor after checking. Could there be a fault with J519 although purchased new? Everything else works ok.
Many Thanks