Hi all i have had my gp for two weeks now and i decided to change the headunit. As i did this and started the car up, the airbag failure light came on? Could it have anything to do with me fitting a different headunit?

I doubt it there is a known issue with out of date/bugged software unless you have got a bit carried away with a set of wire cutters

Known faults/issues;
It is recommended that the vehicle is correctly checked as this list is only intended as a guide & not applicable in all cases.

Fault - Airbag light coming on at start up
Cure - requires airbag ECU update
Status - currently ongoing,later cars ok

https://www.fiatforum.com/grande-punto-technical/89495-recalls-known-fault-issues.html

Oh and welcome to the forum

if you can use the search option many things that can/WILL :devil: go wrong with your punto have probably been done to death in the past

its only 6 months old and i didnt cut any of the original wires.

I was joking about the wire cutting then again knowing what some people are capable/incapable of

its a dealer job it "should" be doable whilst you wait no doubt the resident section moderator will be along at some point to give you a more accurate time scale...

As Andy has rightly said make sure the latest airbag ECU software has been installed this should sort your problem.