Earlier OBD2 code reader
My first aquaintance with an OBD2 scanner was when my 2001 Vectra B threw up an engine check light. That episode is documented here and convinced me of the value of being able to read these fault codes without having to pay a main dealer £60 or so an hour for the priviledge. Unfortunately when I changed my car to a 2006 Vectra C I found that the original scanner I had bought wouldn't connect to the newer engine management computer so I sold it on eBay.

Finding a new OBD2 code reader
My Vectra C threw up an engine check light and I cursed. I remembered all the caveats and connector pin checking that had been needed to find a scanner for the old Vectra plus the fact that it wouldn't work with the new one despite the pins on the connector suggesting it should. I searched and found a forum thread where someone with a Vectra C had successfully used an OBD2 scanner and given a link to the scanner they had used. It was a Memoscan U480 on eBay and was still listed. What's more all those supported protocols and connector caveats were gone - the advert simply said all European cars built 2001 on. It also mentioned that some earlier cars may be supported too. Being a tightwad I didn't immediately buy it though - first I searched for the cheapest one using the Google product search and it turned out to be another one on eBay for only just over £20 delivered (the first one I bought years before was at least double that). As a bonus the seller had thousands of feedback and was still showing 100%. So did I jump straight in? No of course not - I bought it through TopCashBack to get a few bob more off.

Memoscan U480 OBD2 code reader
The U480 arrived very promptly. It looked a bit more cheap and plastic palace than I remembered the older scanner being but after all it was only half the price and the important thing was would it work? After suffering only minor blood loss opening the blister pack I hurried out to the Vectra, paused briefly to check the instructions, and connected up to the socket (hidden under the ashtray in my SRi model).

The code wasn't some obscure manufacturers one like last time it was a simple generic P0304 which the supplied code book informed me was a misfire on cylinder 4. I reset it and resolved to get some new plugs fitted at the next service due in a few weeks time. I drove to town and back on the Sunday and the car was fine. Unfortunately there was another light driving to work plus the car felt a little rough. P0304 again. I reasoned that unburned fuel going through the catalytic converter may result in an expensive failure. Clearly it needed fixing fairly quickly. I lifted the bonnet - hells bells no plug leads on view let alone any plugs. A quick google showed that there was a cover to remove and under that something called "coil packs" (which apparently are awkward to remove meaning I'd almost certainly bust one). These sit atop the plugs which require a mini plug spanner on a long extension neither of which are in my extensive toolbox containing rusty mole grips, broken screwdivers, loose sockets and spanners in all sizes apart from the one needed, and a large hammer with a splintered handle. I'd have taken all this in my stride years ago but remembering almost ampuating my finger on the butterfly valve while undertaking my last repair on the old Vectra I've booked it in for the service early. At least I could tell them it is misfiring on cylinder 4 (I don't doubt they'll still sting me a fortune to fix it though).

Update
Well the main dealer lightened my wallet to the tune of ~ £320 for the service and fix. They reckoned that it needed new plugs and a coil pack. Coil pack?? My eyes are still too watery to search after noting that the wretched thing cost me £120 + VAT (VAT which George Osbourne promptly passed on to one of his cronies so they could bomb Libya) but it seems to be individual coils for each plug thus eliminating those old fashioned £5 a set plug leads. Such is progress.