Dreaded P0420 CEL UPDATED post #59

Check the simple things first.. Exhaust leak(start it up and move your hand over joints before/after the O2s), clean sensors mentioned above, check fuel pressure, check fuel trims/o2 readings with OBDii port reader and torque(android). No need to needlessly throw parts at it.

 

My friend says one monitor is allowed to show not ready but can not show a code and of course, no light.

 

In TX, you are allowed 2 not readies on OBD2 up to '03, (I think)
Only 1 after '03 (I think).
Anyway, you can have 1 'not ready' as long as the light is not on and you have completed 'the cycle' meaning the ECU has tried it's best to 'ready'.

The cheap-o route is a resister (to slow down inputs) and a capacitor (to slowly feed them back in).
Sometimes (if cat is actually working, just not as well as Toyota likes it) the cheapo will 'ready'.

if cat is shot it will not 'ready' but continue on in a 'not ready' state forever. just never trip the CEL.

So if you can have 1 'not ready' by law, all you have to do is build one, drive 100 miles to set everything else and go get checked.
They see 1 'not ready' tell you that's all that's allowed and you get your cert.

 

There you go.

Put it inside, under seat where they can't see it.

 

It it the presence of codes that constitutes a fail. If one of the monitors or more is not ready then the vehicle technically doesn't fail a test it is rejected as being not ready for testing

 

Masking the code is ridiculous.. Fixing the problem is the right way.

 

Sorry to need to be spoon fed here but you're saying (well, most likely) that the O2 simulator will do what I need done?

Sandman, I get ya. I do. The cat in it is new. It runs flawless. A quick Google search shows $800-1000+ for an OEM replacement. I don't exactly have unlimited funds or a desire to unbolt and toss a brand new cat in the dumpster.

 

It will mask the problem from the computer (and inspection place) making the light go away.

Masking the code is ridiculous.. Fixing the problem is the right way.

 

He says he can have 1 "not ready".
That means pass.
The contraption above may or may not 'ready' depending on the state of the cat. but it will not let the light come back on.
They hook up to our ports here, this is how people beat it.

W/o buying cats. You want it perfect, buy a cat. A Toyota cat.

You could try Cataclean.

 

Some people don't want to buy 1000 dollar cats for 20 yr old cars.
If you have the money, fix it however you like.

 

∆∆∆ ya answered as I edited.

This is my point exactly.

 

This guy..

Take some pride in your Taco! Fix it correctly so the pcm is getting the info it needs to run the engine. If you start messing with oxygen sensor signals the fuel calculations get messed up. You will get poor mpg and risk damaging your "dream car"

 

But he states the cat was replaced.. So there is a different issue, the cat wasn't the issue to begin with.

 

What about people using tuners?

 

And that's a possibility. But it's known Toyotas don't like aftermarket cats.

 

There is information stating that on this and other boards. How many of those people have checked/fixed any other issues (Exhaust leaks, bad o2s, fuel pressure, etc) problems before they did that? I stand by the OP doesn't need O2 sims to Fix his problem. If he wants to hide the problem and forget it that's his business.

 

Even TRD makes a 'simulator'.
Is that allowed because it has the Harley, er, Toyota name on it?

 

If it has another prob. (other than it being an aftermarket cat) I agree.

 

So what would be your recommendation Sandman? Curious. Obviously the cat is new. Based on posts here and reading elsewhere, new plugs, wires and O2 sensors won't fix it. Replace an already new cat with another?

 

@thesnowgod You have a couple main options to pass your inspection
1. Check the things being told to check and find out if there is an actual problem that is causing the code(exhaust leak, bad o2 signal, fuel pressure check,etc) - Free

2. Build/buy the o2 sims - cheap to expensive(URDusa solution)

3. Replace with factory cat - expensive and may(probably) not solve any actual problem refered to in solution 1.