Where can I find a diagram/instructions for inspecting cat convertor

Have a 01 tacoma and its throwing p0420 check engine codes. I am looking for detailed images, diagrams or instructions on where to find the cat convertor and how to inspect the seals before considering buying a new 02 sensor or cat convertor.

Any advice on where there is a good diagram for this.. I have located the cat and i know it has heat shields to protect it.

Can take images if you guys are super curious.

thanks

 

It should be bolted on, best way to know for sure if its bad is to take it off... Hold it up to light and see if there is any blockage and try and hear if anything is rattling around inside. If everything looks and sounds goods just get new gaskets and put it back on.. you can also take your oxygen sensors out you should have 4 wires. 2 are for the heater circuit and 2 are for the signal circuit. Put 12 volts DC to the heater circuit then take a propane torch and heat the oxygen sensor and hook and oscilloscope to the signal circuit and check the sin wave. You can google images of what the wave should look like. And you should be able to find the wiring diagram on here somewhere, sorry im not sure exactly where

 

I have been a tech for about fifteen years with a breif 3.5 years as welder in the army.With my time as a tech I have never seen anything but replacing the cat be the fix for the p0420 code. The diagnostic flow chart for both toyota and cadillac (the lines I worked for) state check for exhaust leaks if none found replace converter.The exhaust leaks that would cuase this code would be between the air fuel sensor oand the post cat o2 sensor and this leak would be a large leak.

 

Yeah I should have mentioned in my previous post, on one of my tacomas I had this code and it was the cat

 

O2 sensor range is between 0-1 volt and I believe the heater circuit operates with 5 volts, so connecting 12 volts is not a good thing. That being said, you do need an oscilloscope to properly diagnose an O2 sensor...the only proper way to test a cat is with a gas analyzer, the machine used for smog tests. The way to test it is to take a reading pre-cat and post-cat, post-cat results should be reduced by, at least, 60% from pre-cat(or something close to 60%)

 

Ive tested many oxygen sensors with 12 volts and its worked just fine, and yeah the cat has to be hooked up to smog stuff for 100% but we dont do smog here and most of the time when cats are bad the insides are busted up and you can tell

 

Thanks, with all this good info being said where can I buy a compatible O2 sensor and cat convertor.. Prefer online to support the Tacoma community and to get a good dead..

Paid Firestone $100 to do a "computer diagnostic" they claimed to have tested the 02 sensor and said the best course of action is to replace sensors and cat for a total of $2500.

I'd prefer a more affordable option.

Also tech said that there are 2 sensors on my truck and they both need to be replaced. Is that true? And for that matter isn't there 2 cats????

 

Yes there are two sensors, no it should not cost that much to get done. By the sensors at advanced then go to an exhaust shop if you dont want to do it yourself. They will mark the Cat price up, but it wont be $2500

 

is it true that there are two portions of the cat convert. that need to be replaced?? or is it just the single unit towards the front??/

 

I believe p0420 is the Pre Cat sensor. P0421 is POST cat

your truck also has 2 usually the second one is the one that goes bad.

get a Partnumber from the dealers and go to TOYOTApartszone.com

 

Just a single unit.

 

does anyone know what the part numbers should be that i should order? i am having trouble understanding exactly what and where i should order stuff since there seems two be 2 cats and 2 sensors in all that could possibly be bad.

the good news is i found a shop in my town that said they'd replace the o2 sensor and cat for $250 max if i provide the parts.. not to bad i say.

 

Cant you rod the cat out of it and just run it empty?

 

Of course you could do that.. i considered that myself but I think i'd need my own private island or country because most places have some sort of emission standards and having no cat would certainly raise some eyebrows lol