Need help; Battery Drain
 

1999 Boxster, manual. Wife sometime doesn't drive the car but once a week sometimes every 2 weeks. We have been having an intermittent battery drain, sometimes dead in 3 days, sometimes fine for weeks. Just checked with a test light and the B1 fuse was the draw. B1 is ODB, Instruments Tiptronic and Traction control switch. Could this be it? I would expect some draw there but it was a bright light on the tester. TIA