2008 Aveo Passenger side airbag light on - B2501 and B2502 - Fixed by replacing clock.
For months, my 2008 Aveo sedan airbag light was on and providing codes of B2501 & B2502. I was told that the passenger seat occupant sensor needed to be replaced for around $800. In my case, that wasn't it as the light stayed on (may be different for other folks). The digital clock had been going on & off form about 6 months too - sporadic. I didn't think about connecting the two issues until recently reading another post. I just replaced the digital clock (around $70 including shipping & tax) and the airbag light has not come on since. I cannot guarantee this will solve everyone's issue, but after not getting anywhere with mechanics, I thought I'd try this first. In my case, it worked.