relay a4 (engine compoment power supply relay)
when that relay stopped working vag was reading
* Code Error* *
16575 - Fuel Pressure Sensor Short To Ground
17806 - Rpm signal short to ground
17833 - evap purge valve short to ground
17935 - intake camshaft control short to ground
17446 - (Unknown)
18011 - Internal Control Moduel
17435 - (unknown)
18727 - ( Unknown)
18582 - (Unknown)
by the looks of it , it controls quite a bit
