It really depends on what is causing the light - can be something incredibly minor which would make no difference to it in day to day use or maybe something which will cause running issues.

Try and at least find out what is causing it and try an amicable approach before going legal as it doesn't always work.

(To illustrate that matters are no where near as clear as some people here think I will illustrate with a recent true story involving a dealer local to me. This particular dealer doesn't have a great reputation anyway but basically customer buys what we shall just call a Japanese sports car with an unusual engine configuraiton for £6k. Buyer gets it home, tries to start it and it will not start when hot due to low compression and needing an engine rebuild. Takes it back to dealer and dealer basically says you've bought it, your problem. Buyer is more than a little pi**ed off and leaves said car parked in road outside dealer intending to put a sign on it that it is a wrong-un. Buyer takes dealer to small claims court - dealer (who is used to this!) defends with all vigour and, amazingly wins - they've won 7 other "clear cut" cases this year. Dealer then sues buyer but not through small claims court (so can claim costs) for storage, defamation, loss of business etc. Dealer wins and wins very expensive lawyer's costs. Buyer has currently spent £6k on car they do not have and will not work plus is being persued for £25k by the dealer.)

PD - do you have any further information as to *why* the dealer won that case? As Collos says the Sale of Goods Act should have weighted things in favour of the buyer, particularly as the fault was clearly there when he bought the car, and it doesn't sound like something he could have found out by inspection.

No, I don't. I think it rested on the buyer having to prove the car was faulty at the actual point of sale - the fact that it went wrong 2 hours later meant the case was dismissed.

Obviously I can't name the dealer concerned but they are a fair size outfit and have been prosecuted by Trading Standards for other matters in the past. They're not short of money and can afford good lawyers and defend every case.

Most cases seem to either get settled out of court or the dealer never bothers to enter a defence but this lot stand their ground.

If you have expensive enough lawyers representing you versus a layman doing it themselves I guess it makes a difference.

Legals costs insurance for dealers to cover claims from customers has become big business in the last couple of years and an increasing amount of dealers have it so maybe more and more cases will be defended in the future.

As I have written here before most dealers who act considerately with customers do so because of their reputation and being basically honest not because of the SoGA.

I should add the dealer above deals mainly with high mileage £2k-£8k sort of stuff if that makes any difference.