90% of the cars I've seen with a catalyst inefficiency code had bad downstream O2 sensor, NOT a bad catalytic converter (cat). The ones that did have bad converters had bad upstream sensors and were run that way for months and the rich mixture burned out the cat. I always try changing sensors 1st, then the cat, as if you're gonna change the cat, you'll want new sensors anyway to prevent burning it out. One customer was told by the Volvo dealer that he needed a new cat for $1800. 88,000 miles on the car. We changed his upstream and downstream sensors (probably only downstream bad) and he passed emissions for another 10 years without changing the cat! Saved him $1600 and all legal.

I've had my check engine light on for about 100,000 miles I got tired of looking at it. My solution costed less than a penny. I simply cut a piece of duct tape and covered the illuminated light.

You can do what you want with this information. I am providing it as "for off road use" for legal reasons. A lot of aftermarket parts running on the road today are sold as "off road use only". It's the same idea. If you don't like the content, take the 10-15 hours out of your own schedule and shoot, edit and upload your own video. Thanks for watching.

Record the word "smock" and play it while being tested. Might not get your car to pass but they'll definitely let you go quicker and stay far away from you.

how permanent was this fix?

Lucky you at the gas station.

Pd means pending

Dude, ignore the haters. Thanks for the informational video for off-road use. A lot of viewers from states that don't require emissions inspections are also watching this. Thanks again!

The check engine light went off because you disconnected the battery as soon as your computer system recycles after about 100 miles the check engine light will reappear.

I put two of those on and the light was gone immediately. However, after driving for three weeks, the p0430 came back. Any suggestion? Thank you!

Your a very smart gentleman..... funny how alot of the haters probably have never even seen a scan tool or 02 Sensor. Thanks for your intelligent response.

I know alot of people have done this with good results after installing high flow cats etc. I've never worked on Nissans but I would assume this should work just as well. It's definitely worth a shot! Thx for watching !

Just did this to my 04 Saturn Vue, worked like a charm, passed emissions. I used a scan tool to clear the P0430 after the install of the "MOD", and drove one drive cycle and then had car tested and it passed. Thanks

Bought an 05 4Runner from some clowns who thought they ripped me off. Their ad said "no check engine light and 4wd". Well the truck isn't 4wd, which I didn't prefer anyway and after I bought it the 2nd day, the check engine light plus traction control light crap came on many miles up the road. The car is fine. The code is 0430 and the cat does not need replacing as they probably thought. As far as the other 2 lights...those things come on commonly on old Toyota and Honda SUVs over 100,000 miles. Check it out, but if all is well, do NOT go get ripped off by the dealer.

You, Sir, are a genius! Legality or not - if you're in an area where emissions aren't checked (they don't here), but you want the check engine light off in case another more pressing problem flags it - perfect solution. Well done!

It worked, my car just passed the emissions test. I would have had to pay $1400-$1600 to replace the cat. I instead paid $80 for a floor jack; $45 for a set of jack stands; $10 for an O2 socket; $10 for a set of non-foulers I bought off Ebay (longer 45 MM size, no need to combine two shorter non-foulers).

I did this and it worked. I wish that I had seen this video months ago. Prety simplke job to do. Passed the smog test too, after over 6 months of not being able to. Took less than 15 minutes, start to finish.

I did this on truck, and it worked like a charm. Passed my emissions with flying colors. Thanks for the tip.

2001 Firebird - Had to use a 9/16 drill bit. Very easy job and the engine light is still out .KZread and people posting makes life very easy. THANKS

The "P" in the code stands for Powertrain, meaning the code has to do with engine and transmission components. A code starting with "B" would indicate a body code and "C" for chassis. I would find out what's causing the P0420 code rather than masking it. Normally, it's just a bad O2 sensor or burned wire.