Would my car pass emissions straight after having my cat replaced? (Code p0420)

Might work. Keep us informed there OP. The test the PCM uses is to compare the signals from the pre- and post-cat o2 sensors. If cat is ok they’ll display a known relationship to each other. A shop with the appropriate scan tool can display those signals, would give you an idea if you’ll end up w/a “pass” or not.

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Hey, guys. I felt hopeful about the Laquer Thinner method for clearing the catalytic converter code, but it didn’t work.

As soon as the CAT monitor became ready the CEL came back on. I tried it all: I changed the PCV valve, the oil and oil filter, the air filter, and the laquer thinner.

It looks like I will have to get my cat replaced to pass inspection. I attached a screenshot of the code that’s coming up.

Is bank 1 referring to the cat in the front of the car or the cat underneath the car?

Also, how difficult on a scale from 1-10 do you think this job would be for a beginner DIYer? (I can watch the youtubes)

If the engine is 4 cylinder there’s only one bank.

If the engine is V6 and it has two converters, bank one is the side where cylinder one is located.


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No surprise there .

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Camry’s model-year/engine/transmission?

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2005 Camry 2.4L

There are dozens of success stories in the youtube comment section on Scotty Kilmer’s video about laquer thinner/catalytic converter.

I’m not seeing any particular issues with cat replacement job for that configuration. Likely just a routine exhaust system job. Googling or U-tube may provide some ideas how it is done. It could involve jacking engine, lower subframe to make access, etc, don’t know. Exhaust system fasteners, once estabilished, are often very difficult to remove.

There are some safety issues associated with cats. For example if car wasn’t running correct could be gasoline inside, so common sense says to take all gasoline safety precautions. And I expect breathing dust from cats not a good idea. So it isn’t a routine diy’er job. If unsure, probably makes sense to just hire it out.

Thanks for letting us know the cat-revival theories didn’t work , at least on your cat. Provides actual experience for others here asking similar questions.

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Hey guys, so before I buy this catalytic converter for my 2005 Camry, I want to be 100% sure that I buy the right type.

Is the bank 1 catalytic converter I need the type that’s in the first picture here or the second?

I believe it’s the first.

Do you guys have any thoughts about the Davico brand for auto parts?

Is the catalytic converter attached right on the exhaust manifold on this car? Is it the piece that has the numbers 2808 on it?

Why can’t they just use the OBD I and even pre OBD I vehicle test equipment for emissions and not rely on OBD II and its annoying readiness monitors?

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OBDII checks for lots more problems.

The P0420 code can also mean a bad O2 sensor. I’d have that checked before I spent big money on a cat. OP, you might want to consider having a good shop diagnose and repair this.


I installed a new O2 sensor from Denso about a year ago.

I think its very unlikely thats it’s the source of the problem. I havent put much mileage on the car since then.

2012 Volvo XC60 has a code for slow response for the catalyst monitor O2 sensor. Do modern cars now monitor the monitoring device for an emissions control component?

I understand the need for the readiness monitor for EVAP. It’s hard to manually check that system. But they already have the equipment to monitor a catalytic converter for the pre OBD II vehicles.

Texas exempts vehicles that are over 25 years old, which is now past mid 1997. So we in to the second year in Texas where OBD I vehicles are no longer subject to emissions testing? They must be getting rid of the equipment for those tests now.

You’re right, unlikely it’s the O2 sensor again. Check out YouTube for repair.

Check the input of the downstream oxygen sensor. I have seen Toyotas with a non responsive downstream O2 sensor when the PCM recorded a P0420 fault.

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Don’t you think the likely culprit is the cat since the engine is burning a quart of oil every 1k miles or so?

Also, can you take a look at my post above where i ask about which cat is the correct one for my vehicle?



The front catalytic convertor is monitored by the PCM via the oxygen sensors. The rear cat cannot cause a P0420 fault.

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Here’s where the O2 sensors are located in your Camry.



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