Would my car pass emissions straight after having my cat replaced? (Code p0420)

Good question. OBD II technology (supposedly) verifies the tailpipe emissions are within allowed limits without the emission shop having to poke their emissions probe up the tailpipe, so OBD II saves considerable emissions testing time for both the shop and the car owner. With OBD II, the car also checks the evap system, so no shop testing for that either.

For OBD I cars, the shop has to poke their emissions probe up the tailpipe, and in some states (like Calif) the testing tech must get inside the car and drive at 25 mph and 35 mph on a car- treadmill. The tailpipe must register HC, CO, and N tailpipe compounds all within allowed limits on the shop’s emissions sniffer. The shop next tests the evap system by pressurizing the fuel tank using a gadget they attach to the same spot where you put the gasoline in during a fill-up. This tests all the way from the filler-tube to the evap canister. They have to manually clamp off hoses that would allow the pressure to drop, for example the purge line.

Besides the extra shop effort & testing time, the biggest downside to cars w/ OBD I imo is the Covid risk to the car owner (and to the shop tech), b/c they both have to sit inside the car.

Before taking the final step of buying a new catalytic converter, I might try one more method of cleaning my current one.

Your favorite mechanic Scotty Kilmer along with other auto websites recommend removing the cat and letting it soak in water and detergent in a large bucket over night.

I have a small issue though.

The cat on my '05 Camry is directly attached to the exhaust manifold, so I probably have to soak the exhaust manifold together with the cat. Do you think this poses any risk?

Also, should I allow this part to completely dry before reinstalling it?

The above link is for off road vehicles only and is most likely Spam.

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The site is not SPAM. The person who told me about the site showed me the gadget he purchased. I do not know whether he used it to pass emissions. I would buy a catalytic converter.

What that device supposedly does is defeat the purpose of the O2 sensor which is consider tampering.

You can end up paying a hefty fine if caught.

Tester

So your car had an emissions problem and this device worked for you?

You installed it yourself?

Is it an upstream or downstream sensor?

Doesn’t matter , it is for off road use only according to the web site . That means you will fail an emission’s test .

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@nickc498
Those devices, aka “spark plug non-foulers” do work quite well. You can buy them at most local auto parts stores for under $10, and they’re easy to put on.

As Tester noted, they are illegal.

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My check engine light resolved itself and stayed off for the next three years without any intervention by me until rust caused the vehicle’s demise. As I mentioned in my first post, it seems like a device that would get you penalized, Also, how could something that small match the capacity of a properly sized converter?

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It is a spacer that locates the downstream oxygen sensor 2" from the catalytic convertor. This slows the high/low cycling voltage input to the PCM.

I am not familiar with the inspection process in Texas, in Nevada there is no visual inspection of the convertor for OBDII vehicles. As for the Federal $10,000 fine boogieman, they go after corrupt businesses. I have known many co-workers with modified cars or missing catalytic convertors who drive around without fear of capture by the feds.

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I did an internet search for mini cat o2 simulator and came up with a lot of results of people using them for straight pipe applications like your coworkers. I don’t get the advantage of modifying a vehicle’s exhaust system - aren’t engines designed to run properly with a certain amount of back pressure from the exhaust system?

If these parts are illegal, how are they sold at local auto parts stores?

By being labeled ‘for off road use only’

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Nick:
The parts themselves are not illegal, especially the spark plug non-foulers.

The $50 parts shown in the link that you provided look just like the “$10 spark plug non-foulers” that are sold at local auto parts stores. The only difference is the $50 part in your link has more marketing behind it, hence the higher price.

Spark plug non-foulers have been around for many decades, way before catalytic converters showed up in 1975. They can be used to fake the downstream o2 sensor so your car won’t have any CEL codes when you have a bad converter or no converter. There are lots of youtube videos and webpages describing how to do it.

I’m not endorsing their use. But for the many I see today who can afford to either buy a new catalytic converter or put food on the table, who am I to judge them.

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I believe the major cities in Texas do a visual inspection of the exhaust system. I will have to double check though.

I really appreciate this info.

I’ve been looking into this, and it seems like most of the non-foulers sold at stores have to be drilled into to make room for the oxygen sensor to fit.

I don’t have a vice tool or drill gun, so if I decide to go this route it might be easier for me to order the non-fouler from that link.

Autozone has them for about $10 a pair. not that I am endorsing them. just hate to see you waste your money online.

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Just fix the car, please.

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If you don’t have a drill, then do a search for " Car CEL Fix Check Engine Light Eliminator Adapters - Oxygen O2 Sensor" and you’ll see lots available, that you don’t need to drill and are in the $10 to $13 range. Walmart has several of them.

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I’m not sure if I’m going this route yet. I will most likely soak the cat in water and detergent first.

The spacers offered at Autozone have to be drilled into and expanded for the o2 sensor to fit. I dont have a drill or vice tool.

It looks like there are some alternatives though.