P0420 code

Remove the cable from the 12v battery negative terminal for a few minutes, that'll clear the codes...

I don't know if Scotty Kilmer's recommendation would apply to a Prius, but this is an interesting video anyways....

 

P0420 =

• Gas leakage in exhaust system. [Assuming no hole in exhaust system, which you would likely hear.]
• Air/Fuel sensor (bank 1 sensor 1) [Some have replaced this sensor.]
• Heated oxygen sensor (bank 1 sensor 2) [Some have replaced the O2 sensor before and after the Cat Converter.]
• Three-way catalytic converter (exhaust manifold) [If the above three, doesn't eliminate CEL, then this is likely culprit.]

Start ruling things out before replacing the catalytic converter.

EDIT: I forget if there is a way to test the sensors? IE, w/ a DVM testing for resistance, continuity, etc...

 

How much oil is your car consuming? How much does the oil level in dipstick drop between oil change? Or do you have to top it up (how much)? What interval do you change the oil?

There is couple of different ways to test oxygen or air/fuel ratio sensors but since you have no code about the sensor those works good enough to pass those tests. They might work just bad enough to cause the code or they might be ok. Sometimes you can look at the live data and know from it that the problem has to be with front or back sensor, or catalytic converter.

 

Bently book points to the two cylindrical shapes, closest to the engine as, two TWC (Three Way Catalysts). It makes no reference to the third cylindrical shape.

A genuine OEM bolt on replacement portion w/ the Cats is $1325 from Camelback Toy (Phoenix, AZ). There would be a shipping fee b/c of the odd size. 2007 Toyota Prius Parts - Camelback Toyota Parts - Genuine OEM Parts - Free Shipping
You should Internet search other Toy dealers who sell on-line, as they might be cheaper (or price match), and possibly located closer to you.

I remember reading some people going salvaged or a generic universal replacement. Don't know how well these two parts worked for those individuals.

 

I wouldn't want to use an aftermarket cat unless I didn't plan to keep the car. maybe a low mileage junk yard cat would be a better choice.

 

That probably is a resonator to help shape the exhaust sound.

 

I also have the P0420. I removed both O2 sensors and cleaned them hoping that would help but it didn't. May I ask that someone be able to take a look at this video and tell me what you think? I am not sure of the sequence between the RPMs and the voltage measurements. So me it would appear something is wrong but can't pin point it. I have a P0420 code. See attached of the actual code from Techstream. I want to find out if my issue is potentially with a sensor and not the CAT.

Top graph is engine RPMs
Middle graph is AF Sensor
Bottom graph is O2 Sensor

 

Interesting, keep us updated. I've heard that a product called guaranteed to pass by CRC works sometimes at cleaning up the cat.

 

There are two catalytic converters and a resonator.

Most states don't allow the sale of used catalytic converters except for scrap so finding a salvage yard to sell one is difficult unless you can find a private seller parting one out.

I just sold two old/bad catalytic converters for scrap and got $ 210 each set ($125 for the first bigger one and $85 for second smaller EA6 one)

I have used these before with good results. Actually just ordered two more.
Magnaflow 99205HM | eBay

These are not legal in California.

You can replace either one and it is enough to upgrade efficiency to clear P0420 code. It makes sense to replace the bigger one because the scrap value is higher. Find a local muffler shop to cut out old and weld in new. Make sure you get your old one back. I usually pay $50 labor.

I have never had one come back yet. I have been using them for over two years and have probably had 15-20 installed.

I am in Florida which is probably a better environment for catalytic converter life. Most of the cats I have had to replace were from cars from the north.

 

Thanks TampaPrius. Would it make any sense to replace both? I wonder if their would be any performance gain.

 

I like that you can cut out the old/bad cat and still get over $100. cool

 

I wouldn't bother.

Performance gain? No, it will still be a Prius.

 

What he said.

 

Does the p042 code cause open loop operation?

 

I'm going to try one of these aftermarket cats from Magnaflow. See how long it'll last on an engine that burns about a quart every 1500miles

 

Magnaflow 99205HM Universal Catalytic Converter