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Discussion Starter #1
I'm seeking help from all experts here. I failed smog recently due to high HCs at 15mph. I replaced the stock cat about 5 years ago and have since put about 60k miles with it.

When I had the after market cat replaced there was bits of honeycomb from one of the pre cats from my 1mzfe 3.0L. is missing one of these enough to cause my failure?

What are since thing I can try to pass?
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Discussion Starter #3
It is a 1999 Solara V6.

I do have both upstream (bank1 and bank 2)nO2 Sensors and a single downstream O2 sensor. My CEL just came one this morning, P0420 is the code which was the same code which caused me to change my cat 5 years ago.

I'm not sure how large of a role the pre cat plays, but are there other things i can do to reduce the HCs at the lower speeds?

Thanks!
 

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2013 Subaru BRZ
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It is a 1999 Solara V6.

I do have both upstream (bank1 and bank 2)nO2 Sensors and a single downstream O2 sensor. My CEL just came one this morning, P0420 is the code which was the same code which caused me to change my cat 5 years ago.

I'm not sure how large of a role the pre cat plays, but are there other things i can do to reduce the HCs at the lower speeds?

Thanks!
Yes. Both are important. If the pre-cat o2 sensor is bad, it might not detect extra fuel. Not sure how expensive these 3 sensors are. If cheap, it is a good idea to try 3 new sensors. Otherwise, google others possibilities like exhaust leak. But getting a new cat might still be necessary. You got an aftermarket cat last time, right? It should not be a surprise that they only last 5 years.
 

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1995 Camry LE Wagon
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It is a 1999 Solara V6.

I do have both upstream (bank1 and bank 2)nO2 Sensors and a single downstream O2 sensor. My CEL just came one this morning, P0420 is the code which was the same code which caused me to change my cat 5 years ago.
It would help to have the scanner readings for upstream and downstream O2s, not just a MIL code. Do you have a scanner?
 

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Discussion Starter #6
Yes i use Torque. Would you like to see a log of the voltage measurements for all 3 O2 sensors or something else? Thanks!
 

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Upstream O2s will be hard to diagnose with log data numbers as they change so fast. Better for you to look at real time graph if that is possible with Torque to see changes in voltage. I believe the after CAT O2 should have a constant voltage. It would also help to look at LTFTs. Get your data and do a Goggle to learn what the numbers mean to see if CAT needs replacing.
 
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