P0420

[z5power]

So, this is the error code I'm getting(have to love catalyst effeciency errors). The car also gets bad gas mileage. From what I have read, the issue lays in the pre-cat attached at the manifold. My question is, if I gut it and reset the ECU, will the code come back? If so, is there a way to fool the first and/or second sensor to prevent this code?

I have tried searching the forum, but there doesnt seem to be alot of definate answers on it.

[tehstocker99]

Catalyst System Efficiency Below Threshold

is all that shows up...replacing the cat should fix the code, from what i read

[Pro]

car must be smoking

[z5power]

Doesnt that cat cost a pretty penny?

So, what has been peoples success with gutting it?

I had an 88 Celica and had done that, but it was an 88, so a CEL wouldnt have mattered even if it had thrown it afterwards. I'm just not too familiar with how newer ECU's work.

[gybe]

I think that if you disconnect the device for which the troubleshooter reports to be dead or non-functional, the problem (code) should remain. The thing is that if there's no engaged circuit on that end (e.g. removed O2 sensor) it is pretty much the same for the ECU as if the sensor was broken but still installed.

Maybe I am wrong, maybe not. Let someone experienced judge my statement.

[z5power]

So, is it safe to say no one here has gutted their pre-cat?

[dtatham]

The cats have platinum inside which isn't too good to be breathing in. Avoid the dust and debris. The cost of a new cat isn't worth dying for.

[mannydingo]

I say replace the O2 sensor and hope that's all. You may waste timg and money but that pre-cat is really expensive and you don't find aftermarket cheaper ones, if I recall correctly. What you should do is remove it and look from one end to the other and see if you see light on the other side. If you do, it's probably fine. You can also try one from a junkyard on a lower mileage vechicle. I mean near the 100,000 mile range or slightly higher.

[Kitty]

I'd answer your cel question by the fsm but its currently on loan.

To answer your cat removal question.
I hollowed out a precat about 5 years ago. It threw a cel. I threw a spark plug non fouler on the 2nd o2 sensor(extends the o2 sensor out of the exhaust flow) so it would get a lower temp reading than the first one like it does with a stock pre cat in place. The 2nd cat will fail in about a year of running no precat. So if your into killing 2 birds with one stone go a head and remove both.