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2005 Toyota Camry P2423

After replacing cat back build by Ontirio Exhaust ( in past bought catalytic con for 1994 worked), after placing it I got P2423 bank 1, Evap not. I replaced the upstream and downstream sensors per Monro diagnosis estimated cost 1512 for 3 sensors. My car has only 2 and bought online Denso sensors and replaced. It did not help.
Some mechanic saying the Manifold is not working some said that the cat back is not working. Already spend over 400 dollars and not even close to get rid of rejected sticker.
I used sea foam too, did not help either.

What is this? catalytic con?
The cat back exhaust should not creat the codes you are getting.

P 2423 HCAC-System ( Bank 1) just gave me one mechanic who scanned my car with Snap-on Tablet size tool. He did not know next step, asked me to go to autozone. Same thing was done by Monro who asked me to pay 67 dollars and suggest to repalce all O2 sensors. I did and code is still coming.
Not sure what to do, getting frustrated. Do you think paying dealer $150 dollars will help me to pinpoint the reason so I can just buy those parts and replace? Is YourMechanic site guy will be a good mechanic to help me or they are same as Monro mechanic.? This my CEL nightmare.

You need a new catalytic converter!

Get that thru your head!


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Which one , Manifold or the one in the central pipe with flex pipe?

Sorry, I have little knowledge about car and already spent over 400 dollars listening various mechanics and Monro suggestion to replace all o2 sensors ( their estimated cost was 1000), I asked for help.

This is going to be interesting, Someone answer me that this is cat problem and get it through my HEAD. I asked him which one? Manifold or cat back in mid pipe?

What is creating the problem ? Do I need a smoke test ?

Thank you


There are tests that can be done to determine if the pre-cat is bad.


Thank you,

Is it testing with temperature gun ?


Fault P2423; HCAC System relates to the rear catalytic converter on a Partial Zero Emission Vehicle (PZEV).

Since this problem seems to have started after you replaced the rear catalytic converter with perhaps an inexpensive aftermarket unit and possibly the wrong application the problem is likely with the new part.

I don’t know what warranties are available in Canada, in some states of the U.S. the PZEVs come with a 15 year/150,000 mile warranty on certain emissions parts. The catalytic converters and front exhaust pipe would be covered under the PZEV warranty in CA and NY for example.

Since the original catalytic converter is gone there is no chance for a warranty replacement.

I’m trying to think what that phrase means … lol … I mean any car is a partial zero emission vehicle. Some are just more partial than others. :wink:

Yes, it is something dreamed up in California. 80 proof vodka is 60% water, so it is partially zero alcohol beverage.


Partial Zero Emission Vehicle was a compromise when the zero emission vehicle (electric vehicle) requirement was retracted. This was after GM spent 1 billion dollars on electric car development.

PZEV brings the hydrocarbon emissions to near zero. This brings us air cleaner assemblies that can’t be opened to replace the filter, fuel tanks with the pump sealed in so the tank must be replaced in the event of a pump or fuel level sensor failure and a very expensive catalytic converter for the OP’s car. The government never stops improving things.

Yes, I did Replaced by inexpensive car back and the p 2423 showed up.

No it doesn’t…at least not with all cars. My 09 Focus is PZEV and I had to replace the fuel pump last December. We just removed the rear seats, cut our own hatch in the metal, removed the old fuel pump, and replaced it with a new one. (replace hatch, replace seats). Didn’t need to do a thing with the tank at all. (also got rid of the code I had for a bad fuel level sensor too)

BMW has the sealed fuel tanks, Ford has the sealed air cleaners.

We drove to NY 200 miles one way, drive within the speed limit got 35 per gallon

My bad, did not know that my car has CA emission therefore it was giving that code.

Now has to change rear Cat.

You will need to check the emissions label to verify that it is a PZEV system or if it meets CA emissions requirements. These are sold in may states but in certain states they have a long warranty on the emissions parts.

The emissions label is located on the under-side of the hood on my Corolla. Take a look there.