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2000 toyota tacoma catalytic converter/check engine light

Our check engine light is on permanently in our 2000 toyota tacoma. This car was purchased in California and has the CA smog equipmtn, but we now live in Oregon.

Diagnostics have been run multiple times. The code it gives is for the catalytic converter. We?ve replaced the catalytic converter twice and had the mass airflow repaired. The check engine light always comes back on. We?re wondering if this is possibly due to the fact that the truck is set up for California smog and the cats have all been replaced in Oregon. After we put the 2nd cat in the light stayed off for the first 250 miles, but then came right back on. We had the diagnostic run again and it still came up with the cat error.

We?re not sure if the California cat is different than the ones we?ve had installed in Oregon or, if the computer needs to be reset differently because of California?s smog standards.


You need to post the exact error codes from the computer.

The “catalytic converter below threshold” code is sometimes caused by faulty O2 sensors, which are much less expensive to replace.

It’s hard to believe your catalytic converter needed replacement, unless your Tacoma has LOTS of miles (you didn’t specify).

Please provide more information. Be as specific and detailed as you can.

The move from one state to another has nothing to do with anything.

Hello, bou777;
California has harder restrictions on pollution, if you do a search you will find two types of cat for your truck, 49 states and California. Could it be that you installed the wrong one.
How many miles do you have on the truck ?
I am more interested in the a/f sensor and the oxygen sensor ( you should have 2 before the cat and one after it ).
I want to ask you if you checked it, my wife’s camry had the code P0420 but before I replaced the cat I checked it and got solved by replacing the post cat sensor. My sister on the other hand has replaced it by a mechanic on her 4runner but did not worked ( I suspect because a bosch sensor was used instead of the OE denso - I believe that Toyota electronics and software routine tables are more restrict than other cars ). If you have done all checks, the only thing I can think of - if all other problem makers such as vacuum leaks, etc - is to check with the dealer if there is a new software release for your PCM.
Post here your results, please and good luck with your repair