great explanation! I would also check the spark plugs on wear. I once had a p0420 and did a test on the gas analyzer. It passed the test, so i checked the O2 sensor and noticed sensor 1 (air/fuel) switching alot and also the O2 downstream. I went on and checked spark plugs and they were pretty worn. I changed the spark plugs and did a reset of adaptive values. Since then i always check the spark plugs to be sure the computer is not compensating for worn spark plugs

This guy gives awesome information. A little too fast for us limited do it selfers, but definitely worth rewinding over again.

Great video Oscar! Love your explanation of examining the root cause. Seen many shops load the cannon without any further evaluation. Misfires and fluid consumption are the main killers of catalysts. Also, amazing what's capable with dongle and a phone!

For my P0420 tests I also like to compare the reaction time of the upstream 02 against the down stream O2. I mainly work on Toyota and Subarus (which use AFR for the upstream). 90% of P0420 codes (I encounter) are related to a slow reacting upstream O2 and /or bad spark plugs

Great job! I’m going to steal this explanation for my channel

Nice job Oscar. I was just trying to explain to somebody the other day about this being a pro tool versus a non-tool. This does keep up with even the highest end scanners. You cannot beat this for the money.

This taught me a new way of testing cats. Thanks for taking your time for sharing your knowledge with us!

Best explanation that I've seen for analyzing the PID data, thanks!

U did a hell of a job showing how 2 do it if anyone says it was bad they have no idea about cars truck or for that matter any thing They're just r***** thanks again !!

I think I got it …it’s little be advanced for me ,,,I gonna study it more ..Thanks again appreciate

thanks for this video bro!! i just rebuilt the engine on my moms suv and it also suffered from oil consumption prior to the rebuilt (we bought the suv used). now that i rebuilt the engine, i started losing a bit of power once the engine is on the road after 15-20 minutes. Nothing drastic, but definitely noticeable. I got the P0420 code, and my dumbass cleared it cause I knew i had to probably replace the cat now, but it never occurred to me that it could've been going on ever since the oil consumption. i have a scanner and am going to try out your live data test, and also look into that scanner you're using. i like how it had way more detailed diagnostics.

Good explanation. Keep the videos coming

Great job man

Cool. I had an intermittent P0420, which turned out to be an exhaust leak at the Manifold donut gasket. Worn engine mounts also added to the leak. A new gasket and mounts fixed it (use OEM for these). Downstream O2 sensor was reading lean. Car is a 2006 Matrix 4WD with 225k miles.

Great vid man. Just found the channel

good job man , thanks

Great informational video. My 2005 Honda Civic has the same code and from your video I realize my CAT may be toast due to a very small head gasket leak that likely caused the CAT to overheat due to the coolant and tripping the code. 🤞that it's the O2 instead.

bien facilitoooo when you understand well hopefully soon i get that.... great video

good job Oscar!

Cool video! Usually a leak, sensor, gasket or a bad cat cause this issue.

Hello! Love all of your lessons and have helped me with ase tests. Was wondering if you had an ase 2 automatic transmission course…

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Great content as usual

This was good. Thanks.

Good stuff, I do have a question I have replaced both cat and o2 sensors, it had a multiple miss fire , and I hear while accelerating a big bang coming from the cat, also I have a small leak from the exhaust connector where they joined , but a mechanic told me that that is not the issue because is not between the o2 sensor , is this correct? Thanks

Very good info my friend!

Great video a lot to remember if you don’t deal with cat codes a lot but it makes sense so I saved it mode 6 is very powerful can you do more micsig scope classes

Hi do you believe in using a digital laser temp gauge the one you point or a infrared camera with temperature readings

Thank you for covering MODE 6. 😤

Hey I had a Tahoe with a returning P0420 code, previous techs had replaced cats twice on it, I got it and could not condem the cat, but they wanted me to put another cat on. Code returned. Later found that coolant temp was only getting up to 180F now matter how long it ran. I put in a resister to the coolant temp connector and verified computer could read 200 degrees, it was able to, tested the coolant temp sensor and found according to the temp to resistance chart. Also passed, so I recommend thermostat customer declined and left. My question is, if coolant temp doesn’t not get up to temp how can that effect just one bank and cause the p0420 back? It’s driving me nuts lol

Have you had a new car block you out of the system ? You can pull codes but no live data ,no bidirectional just Codes.

Clicked on the video hoping to get some insight on my wife's 07 Honda Accord, been getting an intermittent po420 for 5 years, the cats aren't cheap for these cars, so I'm glad I didn't break down and get one at the first sign of the po420, car runs great, haven't had any other trouble codes, just don't understand why or how this code pops on for awhile, only to go back off for awhile, if the cat is on its way out, why has it kept doing this for 5 years, I just don't get it

2005 Toyota Corolla le, brand new 02 sensor upstream and downstream, brand new catalytic converter CARB California, brand new battery, brand new spark plug,anyway, no codes and always not ready the O2 sensor i failed in the smog check. Drive cycle is like 2000 miles now.

Wouldn't negative fuel trims indicate that the car is decelerating, since the pcm is removing fuel instead of adding it?

I got a question bro.. i had this same code on my 2008 Dodge Avenger. It was time for me to get my emissions test done, so i bought a new Cat, and both oxygen sensors. I got them replaced and the code went away and i was able to pass the emissions test. About a month had passed and now the code is back. I dont know what to do at this point

You can run on some toyotas the cat monitor , zero mph

Hey man, do you have a shop where you do smog diagnosis? I am local to you and i have been playing parts cannon with my 94 jeep 4.0 for 15 years. im about to throw in the towel. Id love to see if you can diagnose.

Data data data 😊

Hi Oscar jw what’s the upstream and downstream 02 sensor called in tapdon phoenix read data? Thank you

I have been having problems with My 2018 Hyundai Elantra Chacon SEL with a PO420 Code. I have been trying to fix the problem and clear the code so I can get it fixed so I can sell the car. The car has 225,000 plus Miles on it. When I bought the car 2 Years Ago, it had 86,580 Miles. I am the 3rd Owner on the car and I drive for Uber.

can someone who knows what this guy is talking about make a lil bullet point list on what tests to run/pull up and the respective criteria, and the reasoning behind it? Its a lil hard for me to follow cuz he only talked about what to look for but not why, sometimes

Comparing it with Phoenix Max is not correct

Bla bla bla for five minutes, and you haven't started explaining the code yet.