1997 Nissan Pathfinder - Removing cats

Original Post:Can bypassing the catalytic converter be done by a muffler shop? Do they remove the CC or does it stay in place? This is for a geographical area where it is not required.

Follow Up: So, the above query is based on recommendations by a mechanic who said it was fine to do? Your replies indicate it is illegal. Do you think the CAT CONV is bad and that causes the low gas mileage and speed of only 55 uphill? This car has become the money pit. The compression appears fine per mechanic. If I replace the Cat Conv. will that help? Someone said to go to a discount site to order. Other suggestions? I am NOT a mechanic and am reaching out for advice as I am unclear. Thank you for your informative and respectful replies in advance. Appreciate it.

And where is that ? Also direct your question to a muffler shop because the people here are mostly U.S. residents and that would be illegal .


If you are in the US it is illegal to remove the cat, period. doesn’t matter if your state has no inspections or not. It is federally illegal for muffler shop to bypass it.

If it no longer works, have an aftermarket replacement fitted. They are not that expensive and we all breathe the same air.


Removing or bypassing a cat is ILLEGAL in both Canada and the USA. Are you somewhere other than one of these two?

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i know LA has their own requirements that are more stringent than the rest of the us. i assume a city that is ringed by mountains or hills may trap the air and compound poor air conditions. i recall it being bad 50yrs ago but there had to have been much less cars than today. so now with pollution control the air is better? and there are many more cars?

I really do not understand the mentality of cat deletes. You don’t gain that much, if any, performance by doing it. There are lots and lots of places to get more HP from than increasing your vehicle’s pollution output.

i bet it is a price question. OP needs a cat. per the shop opinion. got quote of $800. hmm, can i just reroute the exhaust gases and save some money?

Engine controls expect the cat to be there. Bad idea to remove it.

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55 mph max is good clue of restricted exhaust

I would think there would be a permanent CEL also but I suppose it doesnt matter to this guy if he is thinking of removing the CAT .

i See your mileage drop is theory of bad cat?

Can it be done?

Will they do it?
Not bloody likely!

Should it be done?
Absolutely not!

It’s gonna b e hard for the folks here to say what exact performance problem could be caused by removing the cat from a car. B/c few of us have done that. The engine computer software is expecting the cat to be there, so if it isn’t, hard to say what the effect would be.

About the only experience along these lines I have, years ago on my old VW Rabbit – this was a 70’s car, pre-computerized engines - I removed the cat as an experiment b/c I thought it was causing a performance problem and wanted to do the test; but it turned out the performance problem was caused by something other than the cat. Removing the cat had no effect I could discern at all.

Ah, you figured out you can update your old posts. I try not to do that.
Yrs ago I had a bad choke and fried my cat. Mileage went from 35mpg to 25 mpg. But use changed. I normally drove 250 miles/week but moved closer to work and it dropped to about 100 miles/week. It would have made sense to change cat to restore mileage but I got rid of car. It might work for you if you drive a lot.

It might be acceptable to remove the catalytic converters if you are in Africa, do you know which country you are in?

If there is an exhaust restriction your mechanic can verify this with a vacuum gauge or by measuring the exhaust back-pressure. If you don’t trust his diagnosis try another shop, it is a fairly basic thing to diagnose unless perhaps you are in a third world country.