My little 2007 sport is just about at 190k miles. It's thrown that P0420 code for years now, and the CEL came on briefly oh... say 2 years ago? Luckily it turned itself off somehow and I was able to pass my last Smog inspection just fine (I live in CA), but come September I'll need to have another Smog check. Problem is, my CEL came back on and stayed on about a year ago... I'm pretty sure the cat needs to go, as the emissions do smell pretty bad (especially when i have the windows down and back up into my own exhaust ).

I've been reading up on which one to choose, and I think it sounds like the Magnaflow Part #5461767 might be a decent pick as I can get it from Autozone for less than $400. Is this a good choice? It's kind of hard to gauge whether Magnaflow is good or crappy. I'd go with OEM, but the part seems to be like $1700, which is ridiculous. I could get like 3-4 of these Magnaflow cats installed for that price.

Anyone from California? What did you guys do when it came time to replace the cat?

 

Before replacing cat address the underlying cause: misfire and or rich mixture (may need to run the car on treadmill to check the HC, CO and CO2)
Check downstream O2 sensor reading; sometimes the secondary sensor may not be good
Does your scanner has a life data option? If so look for the cat temperature after driving 10 miles on the highway and post it here ; from experience anything less than 300C will prompt more investigation.
If you are meeting income requirements, state of CA will pay a share for smog related repairs. Most shops are using OEM approved substitute which will work for another 2 years and have CA certification

 

Misfires would cause a sort of stutter when driving/idling right? I only had that a few years ago, but i changed the spark plugs and coils, and have driven about 80-90k miles without any more stuttering.
Do I have to go into a shop to check the downstream O2 sensor? I only have one of those little bluetooth OBD2 things that you plug in and connect to apps on your phone to run diagnostics. Been a while since I used it, but I think the app i have can record some more complicated data. Maybe that's one of it's capabilities.
I don't think I'd qualify for the CAP program, unfortunately!

 

I'm not familiar with bluetooth so I used my Innova scanner. The voltage of downstream sensor should be pretty constant,(between 0.6 and 0.9 volts), not changing every second:

 

I did the voltage check while it was running in idle. It was basically a Sin wave, every second it alternates from about 0.1 V to 0.7 V, back and forth. I need to see if that was for upstream or downstream though, apparently one of them is supposed to be like that?

The cat temperature just kept going up, i stopped watching it when it got over 450 degrees F.

It also did an "emissions check" and found the Cat, o2 sensor, evaporation, and EGR to "not meet" the standards. So that's great...

 

The primary O2 sensor is replaced with AFR sensor that cannot be tested with voltmeter (as it generates current not voltage). I cannot believe though that there are so many failures (not meeting the standards)

 

Emissions

Voltage for Bank 2 O2 Sensor

 

hey kiosade,

did you replace your cat? if so, what brand did you go with? are you happy with it? did it fix your p0420 code?

thanks!
kyle