Hi, I have a 2001 (51) Fiesta 1.25 zetec 5 dr. I am on a tight budget and wondering whether I should be planning to replace the car by the time the MOT is due again in January or whether it is worth keeping, in which case I should start by putting things right now to be cost effective. The check engine light has been on since 2 days after I bought it, no doubt the dealer reset the ECU to give him just enough time to sell it. Performance is fine, I am having no backfires, stalling, problems starting, issues accelerating or maintaining speed. I would say the engine is running well for what it is. I have accurately measured fuel mileage and is consistently around 38. I drive 1000 miles per month and is probably 25% urban, 25% urban dual carriageway and 50% motorway. I'm quite happy with that. During MOT they left a receipt with a few OBD codes in there for me. I have: PO481: Cooling fan 2 control circuit malfunction. PO645: A/C Clutch Relay Control Circuit PO420: Catalyst system efficiency below threshold (Bank 1) I'm guessing the latter is the one in question. Replacing the catalyst is going to be a deal stopper for me. The car runs and handles a treat, although there will be some other work to do. When I was having the front discs and pads replaced the guy noticed the light saying he had the same car and it was just the lambda sensor. It could well be, but it could well be other things as well. What I would like is to keep the car well maintained as I do anyway and keep it going for another couple of years and then hand it to my partner when I can upgrade. Keeping it on the road and well maintained will be expensive anyway without forking out for major work. There was 70k miles on it with a single owner and full service history when I bought it, there is now about 74500 miles on it and it has never given a sign of failure. I am a little concerned about rust which I understand these things are well-known for. Anyway, I realise there is going to be risk involved due to information not being 100% accurate but would anyone suggest it is worth replacing a lambda sensor and keeping maintained or should would I be better off just leaving it be and flogging it when the test is due? I'd like to upgrade to one of those brand new mondeos they look amazing but I'll be happy keeping my old fiesta going for now! Thanks for any advice Ben Edit It is probably worth noting that i've fitted a clean air filter and it passed its MOT while light was on so guessing emissions are OK. I have got to be honest I've been looking up this problem for a while and I'm expecting it is the cat and will probably just have to get rid.