2006 Lexus IS350 P0420 and P0430

Hello everyone!

I'm stuck with this car for few days now i can't figure this out!
when i first got the car it came in with these codes:
P0172 - System Too Rich (Bank 1)
P0175 - System Too Rich (Bank 2)
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
P0430 - Catalyst System Efficiency Below Threshold (bank 2)


I ran the Control the Injection Volume for A/F Sensor test to monitor the A/f Sensor and O2 sensors but to be honest i don't know what i'm looking at
i took a couple of screenshots to see if someone can guide me what to look for

I forgot to mention that i erased the codes and drove the car 2 days for 20 minutes each time and the only codes that comes back is P0420 and P430
i did check for air leaks on engine and exhaust with a smoke machine and i didn't found any leaks

It looks to me like your Injection Volume test showed good results? :huh: All sensors show rich and lean when you commanded the air/fuel ratio. The downstreams lagged behind a bit, and that's normal. The upstream sensors read close enough to stoich with no change commanded, and seem to move equal amounts during ratio changes.

I normally use that test to look for sensors that respond slowly, or to catch lying sensors in the act. For example, if you commanded a rich condition and one sensor refused to read rich, or was slow to change, that'd be a red flag.

What were your fuel trims at idle and while driving?

i only have screenshots of freeze frame for P0420 and when i was driving i took a screenshot one the A/F and 02 but i will check the fuel trims right now and post them

I have more information about this Problem.
I started the car when cold and i took more screenshots when cold start, when purge valve started working and when the cooling fan turned on
also when i was driving on part throttle and WOT

Thanks for the additional info.

I see the trim shift when the purge comes in, but the total trims are still very reasonable, IMO. As a matter of procedure, I'd have like to see a capture of WOT from a rolling stop through the 1-2 upshift, just to make sure there's fuel enrichment capability. Your upstream A/F's did go rich, just not as rich as I'd like to have seen. I believe this is because you 'rolled into' the throttle instead of matting it.

Those downstream O2's are switching quite a bit while driving. That's not a smoking gun by itself, but combined with the P0420/P0430, I think you're done. Check for any TSB's, double check your exhaust, then suggest cats.

(UPDATE)
i double check for any leaks again in the engine and exhaust and i didn't find any leaks, i swapped the A/F and O2 sensors from left to right to see if there were any changes or something, i cleared the codes and drove it 2 days for 15 miles each time and i'm getting only the P0420 now .
i ran the test again and took screenshots for mode $06 and i suggested the both front cats. I don't have access to check TSB's.I'll wil post the results after i change the cats, on the meantime these are the screenshots after i swapped the sensors.