how often should i change the cats? i got 80k on my truck is a 99f150 4.6 2wd

 

I think that "technically" they are supposed to last the life of the vehicle. But alot of "external" factors are what usually contribute to an actual cat failure......... Bad or wrong type of gas, physically damaged, running too lean or rich, fate........

I've got 82k on mine and they are just fine. Got 120k on the wifes grocery getter and it's still the original cat. Still the original muffler and pipe too. No holes or anything.

You'll know when they are bad. The exhaust will either smell really bad. Like rotten eggs, or you'll have zero power. Plus you won't feel much coming out the tailpipe either.

Hope that helps.

 

Change them when they smell, get restricted, or rust through. Not that anyone would know but it's technically illegal to replace a catalytic converter that is still funtioning. So even if you put a brand new oem cat on it's illegal unless your old one stopped working.

-Jon

 

I can't find the paper work, but I "think" it's ok to change out your cats AFTER the vehicle is over 5 years old OR has over 50,000 miles on it........ The cat HAS to be physically broken, if you change it sooner.

I'm just going from memory, because I swapped out the stock "H" pipe in an '86 5.0 Mustang GT with BBK "H" pipe that only had 2 cats instead of the four (nothing wrong with the stock cats). The muffler shop that did it had me sign a form that stated the vehicle was over 5 years old or over 50k miles.....

I think I gave the paper work away when I traded the 5.0 for my F150.........

I'd check it out with your particular state, but I think this is a "standard" policy...........

 

In all honesty your CATS should never fail!

If they do theres something else wrong!
JJ

 

Mine are good so far with 117,500 miles. I think what everyone is trying to say, if you want it changed to be on the safe side, take a hammer and a chisel...
For real, like Jimmy Lee said, if the cats are bad, you have a problem somewhere else and it's time to start tracking.

 

All vehicles after 1995 have OBD II. There should be a O2 sensor after the cats. If the cats fall out of range the sensor will trip the check engine light.

 

If it smells like rotten eggs it is bad.

 

well my original cats lasted until my truck hit 190,000 miles, and the only reason that they failed was because i set my fuel pressure too high and caused the truck to run rich (which clogged the cats). if it wasnt for that little mis-hap, they would probably still be there.