Car:
2004 RX330 awd w/ 174K miles -
Symptoms - occasional P0430 light along w/ CEL light with VSC lights on dash

Since purchasing my car it's been throwing the dreaded P0430 code also popping the CEL along with the VSC warning lights. For two years now I've been simply erasing them while driving all has been fine I guess. Just now I noticed Amazon has both for $183. I just ordered them will replace in 9 days, will report back on how long install took as well as hopeful improvement in mpg... I'll amend this thread as I go.

Update:
Tools - 14mm combo wrench (6 nuts hold header to engine, 10mm socket, socket extension, 14mm socket and impact driver to remove exhaust/header nuts, PB Blaster is very helpful, screwdriver to remove bottom splash guard pins
Time - Front cat - 90 mins to remove, install should go much quicker... rear not so sure this can be done without removing engine will look again tomorrow

Started today before receiving my order. Removed the front Catalytic converter/header, everything went smoothly with the exception of the lower left nut (facing from the front of car) as this is a very tough nut to reach but after maybe 30 mins got it. One exhaust nut that attaches header to the exhaust flange needed lots of coercing with PB Blaster and impact driver. Took 90 mins to remove front cat install should be much quicker/easier. Took a long, hard look at the rear cat... absolutely zero clue how to reach any of the nuts holding header/cats to the block this might be impossbile without removing engine.... I'll look at it again tomorrow. Being my code was a P0430 (front bank), it may be need replacing OR the cats may not be the problem so wait and see
Rear bank - . Access is limited but not impossoble once you've removed the rear most bottom shield. Start by removing the Y-pipe on exhaust... tried removing a couple of those bolts/nuts they didn't budge even with PB Blaster and a heavy duty impact... made the executive decision to not mess with it for now. IF codes shows P0420 then maybe I'll get a torch and dive in deeper. My car is a west coast car with no rust can't imagine how this would be with salted roads/rust frozen bolts worse than mine.

I'll follow a very comprehensive/excellent video to do the install -
Final update
Well crap! No matter how hard I tried I could not get it to properly line up between cat and exhaust, the top continued to leak. The lower flange is about one degree off enough so that the top of the flange will not seal. also there is no bracket to mount the lower shield too, lastly the lower bracket was welded in the wrong place so it cannot be used. I'm done with it sending it back to Amazon tomorrow remounting my old cat I'll just live with the P0430 for the time being until my pride recovers

 

I'm looking forward to seeing how the rear cat is done! Hopefully the Amazon ones work fine and don't throw codes! I do want to do my rear one as it isn't throwing a code yet, but I had to change my front and I figure it's only a matter of time.

 

Ordered them today from Amazon supposed to arrive Tues, not sure if I'll tackle then or wait until the weekend. Supposedly the front goes quick the rear takes a bit more work. I'm hoping my P0430 issue doesn't turn out to be only the O2 sensors rather than my converters... also hoping it improves mpg.

 

The rear sensor only monitors the 02 content; air leaks, etc. cause it to. No effect on fuel/air - only front influences that. It’s just a light, not any other effect. The light comes on very, very early compared to when catalytic coneverter is actually worn. Very unlikely anything is actually really wrong w/the cats, if you did an exhaust gas analysis or “sniff test.” Everythign would likely test a-ok.

That’s why we often just defeat the light and not re-do cats, very rare there is actually an emissions issue.

 

Not sure I understand your reply - Are you saying the cats are not usually the problem when facing the P0430, the O2 sensors are not the problem, or that the cats are not clogged therefore would not likely affect the MPG? What do you see the most common issue with P0430 code and aside from ignoring it what do you see as the likely solution?

 

Subscribed!

I've had the same code pop up once or twice a year and I keep clearing it and hoping it won't come back.

But it does. Lol

Hoping for your success friend.
Details on your progress please. 😁

 

The cats CAN be the issue, but usually it’s a sensor or air leak. If the cats ARE triggering the code, it’s not because they are causing emissions issues, it’s because Toyota triggers the code with an absurd level of sensitivity. A car with “bad cats” per the Toyota light, can fly through emissions testing with 0 problem.

The rear 02 sensors have no influence on ECU control or engine control output values. It only triggers that light/code, nothing else. You won’t see any performance or mpg difference because of them.

The pre-cat sensors influence fuel trim, etc. and are important to keep happy, and to address quickly issues related to them.

Regarding that light and cat functioning, someone on this forum explained it really, really well a long time ago. I can’t recall who because I’d love to give them credit. It went like this:

”Toyota cat and cat warning light logic works like this: Imagine you buy a 7/11 Big Gulp. After a couple of drinks, you are now required to throw it away and buy another one in case you want to drink more.”

Basically that’s correct. I’ve verified that myself by taking a Lexus with two bad cats, per the car, through an emissions “sniff” test. It didn’t just “pass,” it was on the “new” side of the allowable range, not mid-range or borderline.

 

Gotcha... thanks for taking the time to explain. Will let ya'all know how it turns out

 

Yeah, this is a very frustrating issue - big hassle for little purpose at all. Some solutions are to
a) space out the sensor heads (works much of the time), or
b) re-wire the sensors to trigger more realistically. I’ll post this up for reference; it’s hard to find good directions on how to do it.

I have used both methods successfully in different places.

 

Thanks Oro... should replacing the cats not remedy the CEL/P0430 I'll use your suggestion here. With 175K miles I don't mind investing the $180 on both cats, it's a gamble but also 1/3rd of a car payment. They shipped so next week or weekend I'll replace them and report back on time it took, tools, frustrations, suggestions, and ultimately whether it worked. Appreciate your help here. I'v tried the spark plug spacers on my Honda a few years back didn't help.

I had thought cats ran >$600 each... we'll see if this works for <$200 total

 

Leeper,

If you replaced the Cat and that still doesn't help with your MIL and VSC code P0430, here are free online trouble shooting procedures for it.

Best of luck!

Here

 

Thanks so much Tammap... once again you've been a great help in providing pertinent info.

First step is replacing them (whether they need it or not), spray clean all the O2 sensors, reset the ECM by disconencting the battery, then wait to see if it resolved the codes... if not then I'll dive into the info you posted. I'll be reporting back next weekend with update... hoping the replacement isn't too bad/nuts/bolts are not too frozen/rusted.

 

Another step you can try is to insert some spacers w/the 02 sensors. This took care of the issue in the older ES (almost identical overall system as yours). I had to go to the wiring a diagrammed above for the ES.

 

I updated the original posting to keep it all in one place but in my cursory pass looking at how to tackle the rear cat... I'm not sure it can be done without pulling the engine. IF I look carefully I can see one nut but doesn't look accessible the rest can't see at all. I may dive under again tomorrow. Install happening likely Tues when new ones arrive