Cat delete

So I deleted secondary cats and it threw a check engine light can anyone explain this?

 

On board Catalytic Converter efficiency monitor knows something is wrong with the exhaust emission system.

 

I’m guessing there is a sensor after the secondary cats which is detecting an out of range condition.

 

Yes, downstream O2 sensor, also the O2 sensor before the Cat. EPA is on to emissions tampering. Truly does not give you anymore power or better fuel mileage. Easier to leave it be.

 

Of course you're throwing a check engine light lol, you removed mandatory emissions equipment. The ECU is programmed to function normally based on the readings your o2 sensors give.

Removing the cats doesn't do squat for performance gains, if anything it makes performance worse. If you notice improvement then your cats were probably clogged to begin with. You can get high flow cats installed, that would be a better option (unless you live in CA)...but since you removed the cats I'm guessing you don't live in CA

 

Welcome to the world of On Board Diagnostics buddy

 

Did you remove the rear O2 sensors when you removed the cats? Since the sensor is before the cat it shouldn't matter what you do to the exhaust behind them as long as the sensors are still in place. They are used to monitor the efficiency of the front sensors and do not report anything about the rear cats.

What was the cel code that it threw?

If you removed the ypipe to cut the cats out then reinstalled you might have an exhaust leak where the manifolds connect to the ypipe which will cause a cel.

 

So, with the long tube headers it will delete your secondary cats. You can get a defouler adapter or an O2 simulator. Look at URD's website

 

I'm guessing P0420/30 for catalytic inefficiency. URD used to sell an o2sensor simulator but I heard it was hit or miss and that they might not sell it anymore.

Also read about some people successfully making their own o2 simulators using spark plug sockets or something like that..

 

0420/0430 is relative to the primary cats not the rear cats. The rear cats do not work in conjunction with the primary cats. The rear cats are NOT monitored by the ecu.

 

Your rear cats have no effect on the O2 sensor or any sensor for that matter. Nothing monitors them.

 

Long tube headers will eliminate your primary cats, or the first two in your exhaust system. After the front two cats, you have your O2 sensors. Then your rear cats. If you long tube it, get an O2 sim. If you eliminated your rear cats, by way of a y-pipe, no sim is needed.

 

Lol

 

Secondary cats cannot throw a code, the o2 sensors are before them. Could have a leak at the gasket right after the first cats, that was giving me codes a while ago.

I no longer have secondary cats after I had to redo my exhaust, and have no codes after fixing the leak

 

@Liftedlegend pics of what got replaced?

 

cannot get the nuts off my old exhaust manifold..
anyone have experience w/ cheap shorty headers?

These DNA motoring headers are $109. on Amazon / ebay.

stainless steel..
but would eliminate the 1st cats. and also require some custom section of tubing.. which im not really set up to do.

 

Hello guys. I’m new to this 3rd gen. I have a 2021 Toyota Tacoma. I wanna delete the rear cats. I have aftermarket exhaust afe will it make it louder? I don’t think they have sensors and I right

 

You posted in a 3 yo thread regarding an early 2nd gen truck.

Try the 3rd gen forum.

Couple of side notes. Cat removal is violation of federal law.

Just like in music, louder doesn't always equate to better. It's still a weird V6. And loud bad music is still bad music.

 

leave your truck parked in a busy city and time will tell.

 

Seeing he's from TX it'll probably be soon enough. If it was CA, probably by tomorrow morning.