Airbag Light ON: Passenger Airbag Fault codes

[skialex]

Hi, I have a problem with a 2004 3.0 E53 that I cannot get rid of. The SRS airbag light is on, and come back on after a rest in about 20-30 miles or less. My first suspicion was the passenger seat occupancy sensor, so I got a bypass and installed it to test, got the airbag light reset, it came back again after 30 miles. My mechanic scanned the car and this is what the codes say:
Fault codes:
12 (0C) Passenger Airbag Stage 2
53 (35) Coupling in firing circuit, side airbag, front right
59 (3B) Coupling in firing circuit, passenger airbag, stage 2
58 (3A) Coupling in firing circuit, positive terminal disconnection 1

Do you guys have any ideas what those codes indicate and what to do. This is our family car, so I don't wan to ignore the warning light, I need to fix it. For now I am stumped...

Thanks!