Legality of removing 2 of 4 catalytic converters on truck...

[alnen]

Unfortunately I live in an emissions county. My truck is throwing a code for catalytic converter insufficiency on one side. So there is an H02 sensor, then a catalytic converter, then the O2 sensor, then a second catalytic converter followed by muffler then end of exhaust.

There is no sensor of any kind after the O2 sensor. Just a second catalytic converter (same for both sides for a total of 4 catalytic converters). Nothing is being done to bypass or fool the emissions system of the truck.

I want to delete the rear two cats, if nothing else to improve mpg and to a lesser extent the performance of the truck, but also to help save money on these expensive parts.

Didn't know if it was legally some sort of issue with removing any kind of the emissions system? Or if having 2 catalytic converters on a single truck would be sufficient for the EPB.

 

[Rambler]

What kind of truck?

 

[Cadcom]

Are you sure they are cats and not resonators?

 

[alnen]

What kind of truck?

09 tundra

 

[alnen]

Are you sure they are cats and not resonators?

yes from what I can tell from researching

 

[Cadcom]

yes from what I can tell from researching

Any chance they bolt in? My Yukon has bolt in and they can be easily removed and straight pipes bolted back in place. Summit racing carries a lot of cat and exhaust bolt in stuff.

 

[Rambler]

The two front converters control hydrocarbons and carbon monoxide, the two rear converters control oxides of nitrogen. Removing the two rear converters will cause it to fail an EMI test. If the converters are working normally, they do not reduce performance. Just because you have a converter code, does not mean the converter is bad. The code can be caused by a bad O2 sensor, a fuel control problem or an air leak in the exhaust. Have it checked by a good diagnostic tech before you start replacing parts.

 

[alnen]

The two front converters control hydrocarbons and carbon monoxide, the two rear converters control oxides of nitrogen. Removing the two rear converters will cause it to fail an EMI test. If the converters are working normally, they do not reduce performance. Just because you have a converter code, does not mean the converter is bad. The code can be caused by a bad O2 sensor, a fuel control problem or an air leak in the exhaust. Have it checked by a good diagnostic tech before you start replacing parts.

The tundra forums are telling me the second set of cats are passive and redundant... I have confirmed myself that there are no sensors downstream of them.

I'm not saying you're wrong about the function, but this particular vehicle has no monitoring downstream of the ones I am inquiring about.

 

[Zeake]

Move

 

[rockyfatcat]

Maybe y’all know this. But your O2 sensor will create 0.1 to 0.9 volts depending on the temperature. If the temperature falls below a threshold (like 95%) it will throw a code.
http://www.autotap.com/techlibrary/understanding_oxygen_sensors.asp

The catalytic converter burns unburned combustion gasses in a chemical process
https://www.explainthatstuff.com/catalyticconverters.html

So removing the aft two catalytic converters aren't going to fix any obdii codes.
If it is an upstream O2 sensor replace it. If it is a downstream sensor. I would replace it and be ready to replace the associated catalytic converter. Or if you are going to shotgun it and throw parts at it replace both the downstream sensor and the cat