I have a 1998 Toyota Tacoma with 2.4 liter 4 and 5 speed. Got a check engine light and Advance Auto said it was a P420 code. I have to get this truck through smog one last time before I register it as historic. I understand there are off road only O2 simulators that send a "clean" signal. Would this work as a temporary fix just to get thru smog one last time? Underdog Racing makes one.

Replace the cat and the oxygen sensors

Rock Auto has a Walker cat for about $100

Spark plug anti-foulers will do the same thing.

Ditto above. Some of us like to breathe too. This is like asking how to cheat on your taxes.

I got a new post cat sensor and a extended for my Accent. Code has not come back in 3 months.

All new Denso (NOT Bosch junk) O2 sensors and reset the codes and take a few long highway trips and then take it for smog. If that doesn't work you need a new cat.

I get that code on my Honda every so often, usually after a long highway drive or after disconnecting the battery. I just reset it with the Torque app and I'm usually good for months. I've been doing this for years. I just make sure that there are no lights or codes, and it's run a drive cycle before I take it in for the stupid state inspection.

Just get an aftermarket cat and have an exhaust shop on the bad side of town weld it on. I did that last year for my Jeep, was $40 to have it welded on.

To answer your question & not get into an emissions morality thread, O2 simulators will work to pass smog if they use the correct capacitors inside. I know several people who use them in California with no issues.

Exactly. Gut the cat and space the O2.

Ive had luck with running a good injection cleaner, premium fuel, resetting everyhting and going up and down the highway in 4th gear, keeps the revs high and the cats hotter, and going right to inspection after about 50-55 miles. I believe they make a product called cat-a-clean but i cant comment on how it works.

+2

Make sure that you don't have any vacuum leaks. Those can cause the 420 code too.

There is a price to pay for oil consumption.

Time to move to another state