I’ll revive this old thread to provide another data point. I got P0172 and P0175 on my 06 LC (230k mi), except I didn’t have any stalling problems for 3-4 months. In fact the engine ran perfectly despite getting these codes. I’d clean the MAF and clear the codes, they’d pop back up in 50 miles...
I drive the aforementioned 06 LC now. It got the P0420/30 around 185k miles, 2017ish. Kept coming back over the course of ~1yr till install of O2 extenders. SAI: I don't actually recall a code ever showing up, I think I just had the loud fan sound at startup and knew from reading that it would...
FWIW on mine I had cat codes (P0420/30) about 1-2 years before I got SAIS codes (can’t recall what codes but recall loud fan noise coming from the unit). I installed the SAIS bypass kit which took care of the SAIS codes, and installed o2 spacers which took care of 0420/30 codes.
New ones (LC, LX, Sienna, GS) are all gonna be expensive from a quick look. I'd go for a used one and do the gear swap, or do what I just did and stuff an old Tshirt between the seat and lumbar pad. Works great, 5 min job.
Are you looking for a new one or used? Used you'll just have to search eBay (looks like sienna/gs/avalon work for certain years).
85820-60140 is part number for new one.
Installed a Northeastern exhaust bought from UPSW auto parts ($200 delivered) today after my 4 year old bosal rotted out (not a salty environment either). Lined up perfectly, was able to install it solo in about 15 mins. Can't yet speak for longevity but it's stainless vs aluminized so hopefully...
@MissouriLC How is the muffler holding up? Only been a few months obviously but has it already started surface rusting? My bosal rusted out after 4 years salt-free, trying to decide if another bosal ($150) or this one ($200), but not sure how well this will hold up.
I don't think they'd be related. We do have a whole host of charcoal canister/evap stuff on our cars though I've never had issues with mine. Also look around for vacuum leaks. Not too well versed on it.
0455 could be gas cap or vacuum line somewhere (though I'd do a search on here). P0430 (and it's twin 0420) are pretty common, there are a few big threads on them - looks like you read them. I had 0420 and 30 and put O2 sensor spacers on and it works - still passes emissions (but I don't think...
They look like the same filters. Using Mcgeorge Toyota I found PN 35330-60030. Double check to confirm it will fit your vehicle but it looks like the above per google.
I'll let someone else chime in on on torque specs, I don't have a FSM.
Assuming you've got P0420/0430, search that on here and you'll find many a thread. Some folks have luck installing new O2's, some new cats, some nothing works. Research before dropping $$$.
I did find this thread (Check engine, VSC TRAC and VSC OFF Lights - https://forum.ih8mud.com/threads/check-engine-vsc-trac-and-vsc-off-lights.946463/) with the same codes as you have... Doesn't explain the no start condition, but could explain the codes. As for the no start I'd look on mud into...
https://forum.ih8mud.com/threads/hot-starting-problems.1221245/
Lots of threads on here about "crank but no start". Could be fuel pump on its way out or vapor lock condition like noted above. Have you heard any strange whining from under 2nd row seat?
I don't think you'll really hear anything unless the links are broken and the sway bar ends are flopping around unattached. So long as there is rubber in the end links (even if old and brittle), worst you'll get is groaning imo. Crawl under and make sure the ends are attached but I'd also check...
Take serp belt off and 1) confirm noise goes away, signifying pulley is to blame, and 2) check for play/grittiness in each pulley till you find the bad one.
They've worked fine on mine for a couple years without issue. I'd be interested to monitor via OBD the O2 specs, AFR, whatever else and see if everything is in spec -- I'd assume it would throw a code if it wasn't, but I wonder if backing the sensor out of the stream has negative effects.
I also had the P0420/30 codes (thread on it) and O2 sensor spacers worked for me. Still passes VA emissions. *shrug* Long story short, try the easier stuff before throwing new cats on it - lots of people did the latter and still had the codes.