After running out of fuel and topping up with old fuel from a can the exhaust light came on after severe misfires. VCDS says cat efficiency below par.

Apparently exhaust was getting red hot and flames were reported from driver behind me!

 

Driven 10k since, performance and mpg as normal but just failed MOT on emissions so need to do something.

 

I'm assuming cat needs replacing, quoted front one £400, rear £600 for skoda parts. Aftermarket ones are approx third of OE with 1 yr warranty.

 

Can I get away with replacing one cat? if so which one, and are the aftermarket ones reliable and likely to last?

 

Will sensors also need replacing?

Car is '59 plate Fabia 1600 petrol, 36k miles.

 

Suggestions will be appreciated

I thought there was only one cat?

All cars sold after 2001 must be fitted with a type approved converter and could fail the MOT if a non approved one is fitted. Approved ones are stamped with the appropriate markings, the cheaper ones may not be approved.

How far out were the emissions, post your figures here. Perhaps its just the lambda probes causing issues.

2 cats one in manifold and one after. 2nd hand cat route with new genuine sensors would be what I would do. Must be a few low mile cars in brealers.

unburnt fuel in an exhaust / CAT is a CAT killer as it overheats the CAT core until the honeycomb melts

 

the fact you had flames out the back of the exhaust indicates you had lots of unburnt fuel in the system

 

if you run out of fuel are you not ment to wait a while before refilling to allow the cat to cool a bit before trying to restart?