cats

[clive d]

cat has rattled for about 30.000miles now starting2 annoy. is it worth beating the ££££ out of it2 2 make it a straight-though pipe before the honey comb
collaspes and blocks the exhaust limiting performance?

[glock19]

Some says that the lambda light will come on after that. There's two O2 sensors on the exhaust, one before and another after the cat.conv. If this comes on due to a straight pipe, there's some electonic components that can be attached to the rear sensor to simulate the required resistance/voltage back to the ECU.

Therefore any other faults that triggers the lambda lamp will still be operationable apart from the O2 sensor on the rear exhaust.

[Bracer]

Only post 96 cars or those few with 95 OBDII have 2 O2 sensors and will trow a CEL if the cats removed but you can always get a O2 simulator.

Pre OBDII cars have 1 O2 before the cat and wouldn't know the difference if the cat was there or not, but you can run rich depending on your state of tune.