So I've done nothing about the leaky exhaust and it's getting worse, and now the check engine light is on. I may be able to get the pipe welded - but I suspect replacing the whole front section might not be the worst idea - I can get one delivered for £200. Problem is there's a disclaimer on supplier's website stating the ecu needs to be reset - I don't have VCDS. I realise one way or another I'm going to need to get the CEL extinguished - but do I need to change any settings once the Cat's changed? I thought it was a closed loop so the system adjusted itself.... As I being a cheapskate was going to get one of the 30 quid ODB reset tools. I know VCDS would be better but I don't plan on keeping this car for ever.