Hello there, my brother recently got a Seat Leon Cupra MK1 1.9TDI with a PD150ARL engine and his Mass Air Flow Sensor has a live brown wire from the sensor to the live battery terminal. If not attached to the battery it kills the battery, runs rough and takes time to start even in moderate temperatures. But, when attached to the battery it runs as it should. No one knows what the issue is and how to fix this, he is running out of options and is debating selling the car. However, it is his second car in less than a year as the previous one, that being a Skoda Fabia VRS, and that one had issues too and i would like him to enjoy the Seat he has now instead of worrying about this issue. We will appreciate any and all help. Thank you for reading and taking your time to help.