Just posting this as it may be useful when somebody with an A Class does a search in the future due to their SRS/Airbag light coming on. Problem: The SRS/Airbag light started to show constantly on my wife's A Class (2004 car). Took it down to my local specialist and they stuck it on the diagnostics and it showed up that there was an open electrical circuit in the airbag system. On a lot of A Classes the SRS light comes on when a sensor in the passenger seat fails or a contact behind the airbag in the steering wheel fails. However, this was not the problem on mine....it turned out to be the airbag control unit. This is a smallish box of tricks (about the size of a box of cigarettes) that sits behind the centre console and apparently mine is not the first A Class they have seen with the problem. Only solution was replacement and it had to be a new unit from MB as they are programmed to the individual car, so you can't get them second hand....cost of the new unit a painful £461+vat !!....total cost with vat, fitting +dignostics was something like £660 So if you are buying an A Class with a glowing SRS light make sure you get it checked out.