Hi guys I just wanted to share my experience with my gen 1 and that pesky p0420 code or catalyst effiency code.this is getting more and more common as these cars age and buying a cat from Toyota will run around $1200 for the part alone and aftermarket cats are hit or miss and a lot of times require welding.this is something I used to do on my lancer evolution 8 (Awd turbo) when we removed the catayltics to install a test pipe for performance gains. My prius had the code P0420 catalyst effiency below threshold so I figured I would try it on my car since it would only cost me $5 and about a 30 minutes of my time. I'm happy to say that it's been about 300 miles so far and no check engine light!i checked the catalyst monitors via tech stream software and all are complete and pass!i just wanted to share the info and how to with my fellow gen 1 owners with stuff you can get from your local auto parts store. ****Disclaimer***** this may be not legal in your state as the catalytic converter is an emissions component and if you have a code for it chances are it has deteriated and not functioning as it should so it probably will not pass emissions testing. This is just to keep the ECM happy and to keep the light OFF!so if you have emissions testing with a sniffer you are going to have to replace your catayltic anyways sorry*** What you will need: - Drill (Multi or high speed) - 1/2-inch Titanium Drill bit or bit used for drilling steel - 18mm Spark Plug Non-Foulers Part No. 42009 (they come in a pair from AutoZone for about $3.99 to 4.99) - 22mm or 7/8" wrench or Oxygen Sensor socket (7/8" deep well socket) - wd-40 or some kind of rust penetrate Step one You will need to grab one of those Spark Plug Non-Foulers you just bought. Take one of them and brace it against something solid, you will need to drill out the rest of the non-fouler in order for the Oxygen sensor to slide inside it (approx 1/2 inch). When drilling metal, it is best to take it slow. If able, borrow a multi-speed drill that you can control easily. Some kind of oil will need to be applied to the metal a few times during the drilling in order to provide lubrication, if you try to drill without oil, it will dull your drill bit very quickly. Step 2 Once you've finished the drilling of the one spark plug non-fouler, you need to locate your second O2 sensor (usually right after the catalytic converter or the last one downstream on the exhaust pipe) Make sure you soak the o2 sensor with wd40 and give it at least 15 minutes to soak in before you try to break it loose.they usually crack loose and screw off with ease the rest of the way You can purchase a Oxygen Sensor socket (7.99 at AutoZone) this will make your life a lot easier. Step 3 Now you need to screw the de-fouler onto the oxygen sensor. You want to use the one you drilled out first and simply screw it on to the sensor then screw the o2 sensor and the drilled out defouler into the UNDRILLED defouler.then screw everything back into the exhaust where the original o2 went. Should look like the pic when it all said and done. It's easier to leave the o2 sensor plugged in to the car as the harness to disconnect it is inside under the carpet.remeber to always use jack stands when working under your car!! Clear the code and you should be check engine light free!hope this helps some of you guys out
Since the code is thrown when the second O{2} sensor shows no change with the first, the pipe may simply delay the gas exchange and mix it long and slow enough to 'spoof' the control computer that the catalytic converter is running. There is a phase change and reduction in amplitude so mixing fresh with stale gas would look to the sensor as if the catalytic converter had reduced the noxious gasses. IF I were doing the same thing, I would use a microprocessor to spoof the second O{2} sensor and 'have a happy.' In fact, I might as well spoof both sensors to run an extra lean mixture . . . even at high power settings. This of course would be totally illegal not to mention hazardous. Today we barely hear about carbon monoxide poisoning so we've become lax about the safety precautions. Bob Wilson
Made a 500 miles trip over the weekend,still no check engine light car prforms flawless.Even did it to my sister's first gen with the same code,she's also happy with the results
My 2001 (250K plus miles on the ODO) got a check engine light with P0420 code under conditions of unseasonally high mid-day ambient temperature combined with a highway lane closure on a steep up-grade which caused all cars to be driven slowly and most probably with inadequate engine cooling. I reset the check engine light and erased the P0420 code using a medium quality OBD-II CAM tool, and then repeated the very same drive later in the week under conditions of no traffic and normal seasonal low night-time temperature, which included rain, and the check engine light with P0420 code DID NOT REOCCUR. It was unusual for me to use my 2001 on that drive, anyway, as I usually take my 2012, and the east-bound climb up to the nearly 2,000 foot mountain pass is an easy drive on the car, whereas the reverse climb is a very difficult drive for the car (either one), but the 2012 can more than handle this drive, whereas the 2001 has a pretty tough time. As long as I keep the 2001 in my coastal county, and don't attempt the drive over into the inland county, with its difficult return grade, the 2001 seems up to the job, as was proved just the other day during an in-county trip which involved only modest grades and low, coastal temperatures.
I just did this last night on my 2005 Prius. It was extremely tight getting it all to fit in there, but I got it. Hopefully it keeps my CEL off.
Excuse me for saying so, but I hate this "solution." This "solution" turns a clean running car into a gross polluter. Why bother having a Prius if you're going to defeat the emissions controls? That brown haze? It's ground ozone, very bad for you, your family, your pets. I replace my bad cat with a new aftermarket one that cost about $200 including new O2 sensors. My friends at Midas welded it in to the existing pipe for about $100. Even folks in California and NY can order them and have them shipped to a UPS or Fedex store out of state, take a little vacay and have a muffler shop do the install.
Because it masks other codes? Those of us who must do emissions testing every other year can't pass inspection if there's a code.
Tight fit on my 2007 as well. Got by the O2 sensor monitoring test without out the 0420 so I zoomed right over to the smog check place. Win.
Yes. Take a weekday trip to Phoenix or Reno and have the converter replaced. If you can set it up in advance, you can have the converter shipped to the shop where the work will be done. I don't know for sure how CARB smogs your car, but here in Tucson it's just a matter of hooking up to the obd2 port and taking a reading (check for codes.) I had mine done last week, it passed with flying colors! If you do it, I'd have Midas do the work, mine here in Tucson does fantastic pipe welding!
Installed the spark plug non-foulers onto my 2007 Prius downstream O2 sensor (212,500 miles) yesterday. Cleared P0420 code with my Techstream software, had helper drive car around while I observed live data while sitting in the passenger seat, worked great and after driving the car a couple hundred miles, all is good.
As far as I understand getting the Cat Replaced out of state still voids your Smog in California. California does a visual inspection of the Cat To make sure it has the OEM stamp on it, they also check to make sure the O2 is not extended. Of course, there are always techs that see a good OBD scan and don't go just do a quick visual check to ensure you have a Cat.
Only worked for 10 months. P0420 just came back today. That must mean the catalytic efficiency has gotten even worse, to the point where even with the spacers the sensor still detects too much fluctuation. So I guess I'd need a better spacer, with a smaller hole or longer distance to buffer the gas exchange even more. There are also spacers with integrated mini-cats, but who knows if they work better or not.
Because you're cheap and/or poor, you drive a prius to save fuel costs and don't care enough about the environment to invest in expensive repairs. Catalytic converters get destroyed by upstream issues; typically if your cat fails then you also have to repair or replace the engine, or the replacement will eventually get destroyed again. When you could just hack it for a few bucks and forget about it, or worry about it later. I kind-of agree though, our car's exhaust smells really bad with a dead cat. I think smog should always be tested with a tailpipe sniffer, because on-board diagnostics can always be cheated. Then nobody would have any choice but to get it repaired properly. But because it's such an easy way out...
Regarding the cat, I had an non-california honda 1997 crv that failed smog test. It was all good expect for the idle HC reading.was a bit too high. After trying a number of things, it still failed, and then I discovered it had a hollowed out cat. So what surprised me greatly is that it ALMOST passed the CA smog without a cat, it only effected idle emissions. Now maybe its different for other cars, but given a prius doesn't actually idle the engine much at all, not having a working cat is probably not much of an impact on air quality.
I don't think any such claims can be made without doing the testing. Anything else is just wishful thinking.
