Failed state emmision inspection - need new cat conv and throttle body??

You could just try cleaning the throttle body. Clean the throttle body interior and throttle plate (using the minimum amount of throttle body cleaner). With a good luck this might even get rid of the P0420 code.

If you still get the P0420 you could check the live data with Techstream (mini-VCI is cheap and good) and then from that deduce if it’s the catalytic converter or something else. If it’s the catalytic converter you can get aftermarket cat. Or even just somehow (maybe illegal) hide the problem…

 

My daughter's 2003 Honda Civic Hybrid with 275K miles just last month failed the MA state inspection also. She told me she has 60 days to rectify the problems.

You might try the fix recommended above and see if that clears your codes before spending big buck for repair or replacement. My daughter got $500 for the Honda as trade-in for a 2016 Subaru Impreza.

By the way, she has snow on her lawn today in Florence, MA.

 

Damn, lazy of the year award.

Since you clearly don't DIY, price labor for:
1) replacement weld on Universal Cat Converter. $100-$200 part
2) throttle body. used runs $25+ eBay (some just TB, others TB w/ motor), other used part sources in $200 range.

 

A direct fit after market Catalytic Converter is under $300. If you are not a DIYer, there will be labor as well.
Magnaflow 49 State Converters Catalytic Converter - Exhaust King

http://www.partstrain.com/store/details/Toyota/Prius/Eastern/Catalytic_Converter/2007/EAST40712.html?source=gglpla&gclid=CjwKEAjwy8bABRD5osXMovTHpmQSJACfZY0F0Hniu1-1DGruQ5d_YOVQ33naOb0_lt9jBLSbmctaVRoC1Tnw_wcB

 

The P0420 DTC is often due to very aggressive programming by the OEM, that is, this DTC is set when the SMALLEST amount of performance loss of the Catalytic Converter is detected. Given the time and miles in service and the fact that P0420 is EASILY set, I suggest new Oxygen sensors be fitted and the Throttle Body (TB) be evaluated or replaced with a reclaimed part. All this for <$200 and you will likely be good for another 100k or so of driving.

While it absolutely IS possible for the Cat to be worn out, Toyota and Subaru are KNOWN for logging the P0420 DTCs on vehicles that PASS stringent emissions tests; basically proving the DTC is a "false positive" in most cases.

 

Downstream O2 sensor will likely NOT resolve P0420.

Many posts of people similarly situated as OP (Origin Poster): high mileage Prius, hoping replacement of this cheaper cost part will make the CEL go away. Replacement of Cat was the solution.

 

Another option is an acid bath of the Cat, but is generally only a temporary fix. In this thread it lasted 3k: Acid bath and P0420 | PriusChat

P0505 may be an easy fix - clean out and inspect throttle body with throttle body cleaner. If that doesn't work, try cleaning the MAF with MAF cleaner. It's possible it's as simple as a clogged air intake filter or a loose fitting somewhere.

I don't know how the inspection works in your state, but in Colorado for the Prius they just connect a OBD cable and check for codes; there's no actual check of the exhaust emissions like is done on other cars. For this reason, if you can get the car in a state where it can make it for 100 miles without throwing a code, you should be able to pass. Generally if you have any warning light showing, you fail emissions. I recommend never ignoring warning or check engine lights - always get them checked out. It's free to go to an Auto-Zone and get your codes read, then you can Google your way to a solution.

 

Let's see.....

$800 for a worn cat or $80 to replace a worn O2 sensor that *could be* the entire cause.

Hmm.

 

I see:
Weld on Cat ($100-$200 Amazon). Muffler shop welding rate, $100 max. VS your $800 Cat.

O2 sensor can be tested to determine if defective. Why replace a part that may be working correctly w/o testing first?

YoUR approach is different than mine. But hey, it's your car and money. Spend as you see fit.

 

Educate yourself on the whole subject please.

You have completely overlooked serious flaws in the "replace with cheap cat" theory....

The CAUSE of the P0420 is VERY tight operating limits set by the OEM, even experienced DEALER TECHS have difficulty positively determining if the Cat or O2 is the cause with certainty. You can watch the sensor trace and with years of drivability experience, be pretty accurate, but not 100%. Installing an "el cheapo" aftermarket cat is an EXPENSIVE PATCH; yes the light will go out, but will not STAY out for long. The only viable path is an OEM cat, if the cat is in fact, the cause.

 

Oh please. Come on down off your high horse, and ed-ja-ma-cate me. I be ignorant. (Being sarcastic, in case you lack wit).

See Definition #3. Witty | Definition of Witty by Merriam-Webster
​

Let the nuanced discussion begin ... teacher.

Bear in mind, OP does not DIY, so I am making a lot of assumptions. Only when OP has someone more knowledgeable, than he, doing the assessments, will my assumptions be proven correct or incorrect.

Catalytic converters fail for 4 reasons:

1) Thermal Failure
2) Plugged Substrate
3) Thermal Shock
4) Physical Damage.​

I rule out 1, 3, and 4. Here's why.
1) Thermal Failure.

The likely hood of the honeycomb catalyst structure melting, due to overheating will be low. As you know (I am assuming you know, since you are my intellectual superior), excess raw fuel is the primary cause of the honeycomb structure melting. For this to occur, other codes will have also been reported. Also, OP would be reporting the car having poor power because the exhaust flow will have been restricted.

Contaminants entering the exhaust could cause a meltdown too. But fuel is #1 suspect. I like to group contaminants as contributing to #2) Plugged Substrate, which I will discuss later.

Misfires could contribute to thermal failure as excessive unburned gas will be entering the exhaust. Codes would indicate misfires. Now, OP just went for his smog check. It is unlikely the smog check place is running Techstream looking at everything. OP needs to have ALL the codes read, as there may be other codes that the smog check place is not aware of. He needs to go to the dealer or a shop using Techstream, to have ALL codes read.

Malfunctioning oxygen sensors could cause excessive fuel to be delivered as well. However, O2 sensors can be checked and ruled out w/ an oscilloscope or w/ a DVM, per, the Toyota Service Manual:

Upstream air/fuel sensor (aka O2 sensor-upstream):

Pin 1&2 should read 1.8Ω-3.4Ω at 20C (68F); essentially a cool exhaust.
Pin 2&4 should read 10k Ω or higher (no temperature specified).​

Downstream heated O2 sensor (standard since 1996 model year, due to OBD2):

Pin 1&2 should read 11Ω-16Ω at 20C (68F); essentially a cool exhaust.
Pin 1&4 should read 10k Ω or higher (no temperature specified).​

A dirty MAF (Mass Air Flow) sensor. Post #2 (by Valde3) suggested cleaning the Throttle Body. An excellent suggestion. OP states in post #12 that he will entertain the Throttle Body cleaning. An excellent route to take: easy, cheap, and fast. It is a good periodic maintenance item that should be done with some regularity. Although MAF cleaning was not stated specifically, it is assumed that it will get done with the throttle body cleaning.

ECU malfunction could also cause be a cause. However, for this to occur, there would likely be other codes present and poor operation of the car. OP does not state poor operation of the car. Again, OP needs to have Techstream used to read ALL codes.​

3) Thermal Shock.

As you know, this occurs when a hot Catalytic converter meets cold water/snow. The cold water/snow will cause the hot exterior metal housing, to see a major temperature difference, causing the metal housing to contract; a public service reminder: metal contracts when cold, expands when hot. This sudden and shocking temperature difference may cause the hot metal housing to contract, just enough, onto the hot honeycomb structure, to break apart. Often times, this type of damage produces a "rattling" sound. OP makes no mention of hearing a rattling sound.
​

4) Physical Damage

Self explanatory. A physical inspection would rule this out definitively.​

Now we are just left with #2) Plugged Substrate.

Too rich air/fuel mixture could cause this. Codes would indicate this. OP needs to get the car read by Techstream.

Contaminants entering the exhaust:

Coolant and/or radiator sealant- OP does not report a blown head gasket and the other common signs of a blown head gasket (white exhaust smoke, coolant in oil). Coolant and/or radiator sealant (if used) entering the exhaust is obviously BAD and an early death for the catalytic converter.

Oil- Prius are known to burn oil, esp starting near 100K miles; this is the norm. There are exceptions to this, but those cases are rare. OP is at 260K miles. OP does not state what his current oil consumption is. His piston rings may be very well worn or stuck, allowing for greater consumption of oil, into the exhaust. Obviously not good, especially for the catalytic converter. The valve guides may be very well worn, allowing for unburned oil to enter the exhaust. Again, obviously not good, especially for the catalytic converter..

What grade of oil is OP using? A grade heavier than 5W-30 may contribute to a catalytic converter early demise, due to the PCV (Positive Crankase Ventilation) valve. A heavier oil might produce more vapors, which enters the intake though the PCV valve, and get partially burned on the combustion stroke. These excessive unburned hydrocarbons, then enter the exhaust, and onto the catalytic converter, possibly raising the temperature of the catalytic converter. Many use a thicker weight to combat high oil consumption; everything is a trade off.
​

The downstream O2 sensor should have already been tested and replaced if necessary.

OP has a plugged catalytic converter, most likely due to excessive oil consumption. He is not the first, nor will he be the last to experience this problem. This is easily verified by removing the catalytic converter and inspecting the exterior (physical damage can be ruled out) and interior (maybe broken catalyst honey comb structure, maybe partially melted honey comb structure, maybe heavily coated catalyst honeycomb structure; a lot of visible light should be seen from either end, which may b difficult due to the bends in the exhaust pipe).

Yup, a parameter has (or parameters have) been exceeded, thus the CEL.

Yup, cause some are not the sharpest tool in the shed. There are many techs, very few GOOD techs.

Earlier cars yes. Which explains why many will opt for replacing the O2 sensors first, before going with a catalytic convert replacement.

The Prius, no. Toyota provides very specific testing parameters, listed above. This does not preclude one from pre-emptively replacing the sensor(s), as a precaution.

Expensive is relative.

Upstream Air/Fuel sensor (8946747010), $162.33
Downstream heated O2 sensor (8946547070), $125.06
https://lovetoyotaparts.com/parts/2007/Toyota/Prius/Base?siteid=215143&vehicleid=189812&diagram=8545170

Replacement universal catalytic converters run the price gamut based on non-CARB: weld-on vs bolt-on.
Amazon gives a good idea of non-CARB weld-on ($47-$99) vs bolt-on ($260+); Amazon link

The only source of CARB compliant catalytic converter so far appears to be Toyota.
Part(1741021500), $1,425.13. https://lovetoyotaparts.com/parts/2007/Toyota/Prius/Base?siteid=215143&vehicleid=189812&diagram=8545165&diagramCallOut=2
​

Patch, yes; if the cause of the problem was not fixed.

Assuming OP has a very high oil consumption rate, ANY replacement catalytic converter will not live a long life irregardless of the type of replacement catalytic converter. How likely is one to replace the piston rings and/or valve seals, to address excessive oil consumption? One will most likely get rid of the car, or a cheaper non-CARB catalytic converter. A used lower mileage engine, is an option, but most will probably opt for a replacement car.

Let me educate you on replacement catalytic converters. There are two main classes of catalytic converters: CARB certified and non-CARB certified.

CARB catalytic converters:

* Achieve the same emissions standards to which the vehicle was certified; replacement catalytic converters are now vehicle specific and pricey. CARB catalytic converters are likely made with more catalyst and operate at higher temps, allowing for a cleaner exhaust.
* Have a 5year/50k mile warranty.
* OBD2 compliant w/ 1996 & newer vehicles.
* Have a permanent label/etching showing CARB Executive Order approval number, manufacture part number, manufacture date, and proper direction for installation.
* Required replacement for CA & NY vehicles.​

non-CARB catalytic converters:

* Made to a lower standard, but will work; more exhaust gases (CO, HC, NOx) will likely pass.
* Some do have a 5year/50k mile warranty.
* Outside of CA & NY, one may be able to have a non-CARB catalyst installed on a Prius, even though all PRIUS are CARB certified.​

 

I got a low mileage "total loss" Prius for $1000. Its exhaust system saved me the cost of the P0420 problem and the throttle body. Replacing both took about an hour and was no more difficult than putting the car on jack stands


iPhone ?

 

Too funny. Essentially a used Cat and all kinds of spare parts. Nice!

Where did you buy this low mileage insurance write off? How did you learn or come across it?

 

Remember, you ASKED for it......

Seems you left some out, such as:
5) Lead (or other chemical) contamination
6) Depleted Pl/Pu
7) Incorrectly diagnosed - be that by assuming correlation to a specific DTC w/o further investigation or pure ignorance

WRONG, again I implore you to educate yourself and not parrot what you read on the 'net, which is often wrong and more often ill-considered.

"Melted" catalytic converters DO result from excessive EGTs, on that one point you are correct. The CAUSE you have exactly backwards, it is LEAN conditions that cause higher than normal EGTs in gasoline powered engines, not rich as you claim. In point of fact, most OEMs ENRICH the AFR during idle periods in "N" or "P" to PREVENT high catalytic converter temperatures. Wow.

See response to #1 above, still wrong.

Again, EXCESS fuel does not overheat cats.
​

ROFLMAO....

Really? You assume a MAF cleaning would be done at the same time as a TB cleaning? That's like assuming they will replace the REAR brakes at the same time as the FRONT. Not only unnecessary, but ill-advised if CPM is a consideration.

What does cleaning a TB do for you or more specifically your engine/car???? Not interested in MARKETING hype, but fact-based results.

How does one clean a MAF sensor? I know how to and more importantly, how NOT TO do it and there are a great number of vehicle where this is more than ill-advised; read detrimental.

How would the ECU malfunction to cause this and what codes do you suggest would result?​

​

Cracks in the honeycomb are exceptionally rare, they DO happen but since the adoption of OBD-2, very-very rare.

Physical damage is not a failure of the cat, it is damage. Is it within the realm of possibility that a P0420 DTC would be logged on a thermally shocked or physically damaged cat? Yes. If EITHER of these conditions are found, it WILL need to be replaced.

With no high EGR flow codes, this potential can be discounted, not out of hand, but highly unlikely. Any "plugging" of the cat WILL increase EBP and consequently result in higher than expected EGR flow. This will be picked up by the ECU as reduced airflow thru the MAF. There will also be NOx impacts that are detectable by any decent emissions analyzer.

What are your suggested failure criteria?

Lots of conjecture in that statement.

No, because POSITIVELY condemning a catalytic converted with ONLY a P0420 DTC REQUIRES much more knowledge of the interactions between the different sensors and actuators than most have experience with. The simple fact is, Toyota diagnostics do NOT instruct a tech to simply replace the cat due to a P0420 DTC.

CARB or not is meaningless in terms of quality/durability. Thousands of people have had Subaru and Toyota cats replaced with "will-fit" cats only to have the SYSTEM set the P0420 all over again.

P0420 is set when the ECM detects conversion efficiency is below a PRESET threshold, Toyota and Subaru are notorious for having VERY tight operational limits; MUCH tighter than other OEMs. Therefore, you often get the P0420 DTC on these brands when the converter is still operating WELL within emissions limits, that hardly constitutes a "failure".

 

All this makes a lot of sense to me. After 300,000 my 2005 started burning a quart of oil every 5k, the check engine light on,P0420. Since I was still getting 42mpg I figured who cares if my O2 sensor is I ignored it. Drove from Fresno to Reno 8000 elevation, literally melted the welds at the exhaust Manifold, at 7000 feet my Prius started sounding like a Harley and it got much more powerful too. I kinda liked it though the CHP noticed it all to much, an unmuffled Prius at 3200 rpm going past you at night will disturb a ‍♀️. But at now 46mpg and approaching 400,000 miles on one engine I couldn't help myself. I kept driving, earbuds helped!
Long story shortened I only got to 397,000 miles when she lost power going up the 4100 Grapevine back to LA, with headphones on I didn't notice she was heating up (slow leak in radiator, I replaced her engine and Transaxle and exhaust system from an Insurrance total loss I picked up for $1000. I swear she gets 46mpg now unless there is a headwind at 75mph.
Epilogue burning oil will clog your exhaust, clogged exhaust will heat exhaust manifold and you will eventually pay for a repair $32,000/397,000miles is .08¢ / mile I can afford one and a new Prius


iPhone ?