They charged me £262 for the diagnosis and re-assembly of the car. They reckoned it actually took around 8hrs, and they charge £99.95 per hour, so it wasn't as bad as they first threatened. But it was still an incorrect diagnosis.

We don't have an emission warranty or anything of the such in the UK. Basically if it's outside of the manufacturer warranty then you're only covered by 3rd party warranties if you have them. This one was given to me when I bought the car. It was a one year Jaguar Select warranty. I bought it used from a Jaguar dealership after its previous owner traded it (and an old XJ8) in for a shiny, new XJR. It didn't cover the whole car, only parts explicitly mentioned in the policy document, which wasn't much. It didn't include the ECU, or any part of a forced induction system except for a turbocharger unit. In fact, it covered sh*t-all and wasn't really worth the paper it was printed on. It was free, so perhaps I shouldn't complain too much.

They did give me the exact fault code but I don't have it to hand right now. It is an EGR code. But it would have thrown a dashboard light, and I had nothing of the sort. A few months back, I had an issue where the secondary air injection pump stuck on. I think that code was historic and related to that earlier problem. Something they should have known, especially since they looked at that earlier problem.

I had a word with the dealership and they've given me £200+vat off a service (which is now due) if I take it to them. It's due a good service, so I could definitely use that. If I take legal action now then it'll almost certainly be rejected because they've made me a “reasonable offer” of reimbursement. So I'll probability take them up on that offer, although it does mean handing the car back over to those numpties. How much damage could they do with a service!?