When you connect the squib on the air bag, you have to hear the connector audibly click. If it didn't audibly click then the bag is not connected and that will give you the SRS lamp. Disconnecting/reconnecting air bags do not set the lamp if done correctly and there should be no need to change the crash sensor (unless you had an accident and the bag or ETR's deployed).
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.