Just to add onto an already well put post, if you get a code for either the passenger or drivers pretensioner there is an option between all the clicks and getting a new one. Under which ever seat you have to code for there will be a yellow connector with 2 wires, will usually be seen from the front of the seat underneath.
You can put some dielectric grease into that connector, this can be sourced from any little or big auto parts store. Just be careful not to let the grease from the 2 pins make a connection. If this doesn't work then odds are it is time for a new one.