Many ebay sellers are offering OBD scanners at very competitive prices.
http://www.ebay.co.uk...t&hash=item336979a2f8
The above unit looks quite reasonable.
Cheaper OBD scanners are available, but there functionality/userbility will be compromised.
Anyone owning a vehicle manufactured within the last 10 years should have access to an OBD scanner. It will allow you to determine the reason for the vehicle engine warning light illuminating.
I paid close to twice the price of the one above, two years ago.
The scanner attaches to the vehicle via a scart like connector, usually accessible from within the cabin – the socket being located under the dash or behind a removable cover.
See this wikipedia link for more info on OBD.
http://en.wikipedia.o.../On-board_diagnostics