O2 sensors and cat

Hi All new guy here, I have an 01 tundra that I have put 150k on .Looks like I have the cat underperforming code , I was wondering where everyone in CA buys a replacement cat and 02 sensors that are CA legal
thanks
Carl

 

Since your in the worst state ever and HAVE to pass smog. Go with OEM to avoid ALL headaches or others can chime in with aftermarket brands that have worked. But usually, aftermarket cats and o2 sensors do not play well with our trucks

 

Check which bank it is and swap the left/right sensor. If the code comes back and it's on the opposite side, you have a bad sensor.

 

www.densoautoparts.com and be sure to pick the "EXACT FIT" sensor, not the universal. You never, ever want to cut your O2 sensor wiring.

Look up your part number there, Denso is the OEM manufacturer. Buy the parts from anywhere on the internet EXCEPT scAmazon or fleaBay, any storefront that validates their inventory. This is a common counterfeit part, along with spark plugs and other electronics. Most people on here prefer Summit Racing or RockAuto for the purchase. They typically beat scAmazon pricing. fleaBay is just full of knockoffs, period. scAmazon has no control over their inventory, even if "fulfilled by scamazon".

You didn't mention if you're V6 or V8 and that matters significantly. I'm going to assume V8 because you say "cat codes".

If you're throwing P0420 code, it's recommended to replace the upstream AND downstream on the driver side at the same time.
If you're throwing P0430 code, it's recommended to replace the upstream AND downstream on the passenger side at the same time.
If you're only popping one code but not both, verify in Denso's catalog that the upstream and/or downstream sensors match part number; if they do, you can swap between sides as @AnnDee4444 said. However, sometimes RWD and 4WD don't match parts between both sides.

Note that sometimes Denso refers to the upstream sensor as "air/fuel ratio sensor" or "AFR sensor". Downstream is always called "Downstream" in their catalog.

Note that those codes can pop if you've got bad seal or leaks also.

If you need help confirming your part numbers, tell us what engine, what cab type, what trim package, and if you're 2WD or 4WD.