P0420: How to diagnose origin of problem

282K miles is a GREAT life for a Cat.

Check this out...
Look upstream for the culprit in a converter failure - Eastern Manufacturing

 

Highly unlikely CAT was every changed.

Death of the CAT is most likely due to the engine burning oil. This is common in Gen2 Prius, w/ high mileage. If you are not checking the oil level on a regular basis, start now. Too many posts of people never doing this, causing premature engine death due to insufficient oil, resulting in insufficient oil pressure, producing metal on metal wear.

If you ever see this warning light, shame on you. This is an oil pressure warning light. IT IS NOT A LOW OIL LEVEL LIGHT.


Try to find a muffler shop to cut off the bad CAT, then weld an aftermarket CAT in its place. Aftermarket CAT is $100.

$1336.25 for a genuine OEM Toyota CAT. 2007 Toyota Prius Parts - Camelback Toyota Parts - Genuine OEM Parts - Free Shipping Its a direct fit, bolt on. You will have to contact Camelback Toyota to see how much they charge for shipping.

Maybe a road trip down South?
$1357 at San Bernardino Toyota. 2007 Toyota Prius Parts - Toyota of San Bernardino Online Parts Store
$1357 at North Hollywood Toyota 2007 Toyota Prius Parts - Discounted Toyota and Scion Parts and Accessories
Or call your your local Toyota dealers to see if they can beat/match these Toyota dealers.

 

Yes. CA and NY don't allow for weld-on aftermarket replacement CATs. I have never had any Smog Check station ever inspect the exhaust system, esp looking closely at the CAT. Who's to say you didn't buy the car like that, unknowingly?

If you regularly check the oil level, in any car you own, and top off, you will likely never see that oil pressure warning light. Now a catastrophic engine component failure due to wear or impact from road debris, can cause sudden loss of oil, producing a low/no oil event, resulting in low/no oil pressure.

I am not aware of a CAT being washable.

All the products that claim to clean/restore a CAT have opinions on both sides: works/doesn't work. I have yet to see any maker conduct a controlled test to back-up their claims. Read this for yourself to decide if you are throwing money away. Cleaning additive can't restore a failed catalytic converter - StarTribune.com

One tank of gas giving you a 2-3MPG improvement, is too small of a sample to celebrate. If you saw this same 2-3MPG improvement, for each of the next 5 tanks, then you can celebrate. One tank could be a fluke.

 

P0420 can be raised on any car and means a problem with your emissions system.

• the catalytic converter itself
• O2 sensors
• any leaks in that system

 

Don't know if those markings belong to the original CAT; never had to look at the CAT that closely. Perhaps inquire at your local Toyota parts department?

Did you not expect this high mileage Prius, to require replacement of various wear parts? You are aware that nothing lasts forever, esp if it is being used? It may very well be that the CAT is actually worn out: the metal(s) Platinum, Palladium, and/or Rhodium are depleted.

Penny wise, pound foolish. Lets see, pour a gallon of Pure lacquer thinner into a half filled gas tank. Drive 150miles. Rev the car to 2500RPM for 30min. Something tells me the rubber bladder, inside the North American Prius gas tanks, will die an early death. Your car, your money, do as you want.

Soaking the CAT in soapy water, overnight, seems less damaging. If the

Your "cleaning" thoughts assume that the CAT is not damaged and the precious metals are not depleted. If this is the case, no type of cleaning will revive a dead CAT.

If you are crying about a CAT replacement, what are you going to do when the HV Battery goes out? Try looking at an expensive repair by amortizing the cost in terms of miles. $1500/282,000 miles = $.005319/mile This repair cost you one half cent per mile.

How are you calculating the MPG? Are you doing old math (miles driven between fill-up divided by number of gallons filled)? Are you relying on the MPG calculator display and resetting this gauge every fill-up?

Beliefs/feelings of improved/increased power are subjective. Only a dynamometer will give an objective result; but this would require a baseline (before CAT cleaning), and a few after CAT cleaning measurements, to validate your belief.

 

had the same problem: the check engine light came on and the p4020 code indicated a bad catalytic converter. I'm going to try
Cataclean as I have nothing to lose

 

Hey guys, my Cataclean converter cleaner review - Worked Great! Put it in and followed the instructions. Used just 1 bottle and so far light hasn't come back on.

 

Interesting thread.
We had another thread a while back about soaking the cat converter in a solution (I forget what chemical is in it). Basically the zinc/phosphorous (ZDDP) from the lube additives needs to be cleaned off.

I also note the mention to NY/CA not allowing after market converters, does that mean the other CARB states (OR etc) you can?

 

It's a soak made up off citric acid and oxalic acid. Works short term, light will come back

 

Hi Gabriel, I know this is an old thread, but did you figure this out? I am in the same situation as you. I really want to be sure the CAT is the problem before throwing money at it. Luckily, in TN there's no inspection. But I am trying to not remove the CAT completely and do some hack on the O2 sensor to get rid of the CEL that's now on.

 

If you do not have an inspection, you (1) have time on your side, and (2) you can replace with much cheaper cat from EBay. The CARB state drivers are stuck with using OEM equivelent which is ultra low emissions (expensive platinum- which us why they get stolen in Ca.).

To understand cat performance, one approach might be measure CO and other tailpipe emissions. I have tried to measure CO from my Prius using a home CO detector and it was basically zero non-detect except for the first several cold minutes, CO was slightly over zero maybe 100-ppm. Before cat converters cars put out 6-8% CO (60,000 to 80,000 ppm). In my state I suppose I could ask the inspection guy to do an off-the-record emissions test (Prius is exempt). If I saw anything over maybe 1000-ppm when warmed up that would be a clue that when cold, it would be probably much higher.

We do not have much data on what a P0420 means in terms of emissions. I do not know if the cat still works acceptably or not when the code it thrown.