Not really, unless you have a spare key.
You'll have to get a new chip then get it coded to the car using dealer-level diagnostics such as tech2, vauxcom, opcom etc. Many independent workshops have this now, dont pay main dealer prices.
You will need the immobiliser code, which is on your "car pass"card. If you dont have it, that'll be another £20 to Vauxhall.
Dont bother buying a second-hand key/chip off ebay, it wont work.
vaux, November 2009
