The connectors that go faulty are on the new micra k12 not the old shape k11, If the local garage could not read the fault it suggets no communication to the air bag ecu is the light flashing or staying on permanantley? have you checked the air bag fuses? this is a quick easy thing to check before going to a dealer.
An air bag light which stays illuminated all the time could mean a few things these are Air bag and/or seat belt pre-tensioner has been deployed or air bag fuse, diagnosis sensor unit(air bag ecu) or harness is malfunctioning. you can also put your car into diagnosis mode for the air bag and it will give you a flash code i'll run you through how to do it.
1. Turn ignition switch on 2. After air bag warning lamp lights for 7 seconds, Turn ignition switch off within 1 second. 3. Wait more than 3 seconds 4. Repeat steps 1-3 three times 5. Turn ignition switch on
This should put you diagnosis mode it will then give you a flash code which are quite difficult to explain i can fax you the page if you have a fax number or explain it to me and i'll try and match it up. If for some reason it won't go into diagnosis mode it may have to go on a nissan consult computer.