2007 LX470 — Dreaded PO420 code

[RedMule]

Need some help from the collective wisdom of the Hive Mind!

Owned the truck for the last three years, during which I've just been living with the CEL, VSC TRAC, VSC OFF lights.

I've performed a lot of the baseline maintenance—timing belt, AHC, heater T's, new radiator, new exhaust, and more—but the PO420 code has been a constant.

After getting the timing belt done, mileage briefly went up to 15+ mpg but now back in the 12mpg range, and the CEL is back.

Just spent some money on her getting the knock sensors replaced (rodent activity) and did the starter while they were in there.

Sadly, did NOT discover 2001 LC's thread on the SAI issue until they had the intake manifold back on. S.A.I. Modification in VVT engines to prevent its failure! Alert Alert - https://forum.ih8mud.com/threads/s-a-i-modification-in-vvt-engines-to-prevent-its-failure-alert-alert.1271108/#post-14193194

Mechanic is recommending replacing O2 sensors.

I would like to try the Katakleen method one more time.... or if anyone has a different suggestion, I'm all ears! This is getting a little tiresome, but I love the vehicle and am committed to getting this fixed!

 

[BullElk]

I have used the spark plug non fouler hack and it has worked very well at keeping p0420 code nonexistent. Lights may come on twice per year.

https://www.autozone.com/ignition-tune-up-and-routine-maintenance/spark-plug-non-fouler/p/dorman-spark-plug-non-fouler-42002/720789_0_0

 

[Bisho]

Denso O2 sensors are actually pretty reasonable on Rockauto.

 

[Coin]

New o2 sensors fixed my code
Just disconnect the battery for an hour or so.

 

[2001LC]

You can try swapping o2, one side to other. See if makes any difference.

But all I've seen P0420 or P0430 or both, swapping o2 or A/F sensors, had no effect. CAT was bad!

We must always determine cause of CAT failure, befor replacing it. Or risk damaging another CAT.

Since you've had P0430 for 2 years, assuming 10k to 30K miles. Without a P0420 or any S.A.I DTC by now. It's suggest a bank 2 only issue.

Some bad CATs, are due to a bad MAF. Which in the short run, may just burn-up one CAT. Left unresolved, usually takes out both CATs.

Only one bank, I look from fuel injectors down stream to back of that CAT, on that side of vehicle (Bank 2 right (PS) side) first.

1. Did CAT take a hit, damaging it.
2. Did flood waters or rodent clog it. Unusually affect both CATs, but can be just one.
3. Any air leaks, in exhaust. From head to A/F, o2 back of CAT. (note VVT have A/F sensor forward and o2 rear sensors. 98-05 use only o2 sensors.
4. Cylinder Compression issue. This can be rings or valves or both.
5. Intake manifold air/vacuum leak same bank. I've never seen a warped intake manifold on a 100 series. But I have read of some on Tundra VVT being warped. Checking for vacuum leaks, can be revealing. With vacuum leak, A/F mix leans, ECM compensate with extra fuel. Fuel or oil in CATs, can ignite.
6. Fuel injector not working properly. This can be clogs or excessive flow. Monitoring fuel trims can be useful.

Borescope is very helpful:

• Run it in A/F and o2 sensor ports. Inspect CATs.
• Check S.A.I filter.
• Check cylinders and valves.

Vacuum gauge also useful.

• Max 5 PSI vacuum gauge, used to test exhaust back-pressure. .5 to 1 PSI is unrestricted.

__________ S.A.I.:

S.A.I filter failure, eventually affects, both Banks. Which some, nay take many years before either or both banks have issues.

Since your now two or more years and many many starts and miles (I presume) since first P0430 DTC. This is not likely due to S.A.I filter. But do inspect filter. Which a borescope can be used to see if filter intact or missing, in just a few minutes without pulling IM again.

DTC may start at just one CAT. But will spread to other CAT and the S.A.I system eventually, when filter has failed. Not correcting will eventually take out the S.A.I system, engine and both CATs. About $23k ($4k S.A.I system, $15K engine and $4k CATs,) in damage, if all new replaced at Dealership. All due to, a tiny little filter failing!

The S.A.I. filter mod is a must have. Sooner or later ALL S.A.I. filter will fail. Either replace the $600 pump (blower) periodically, which houses the filter. Or mod to use an easily replaceable $20 motor cycle filter.

When filter fails. Will get various DTC (codes). The DTC typically will not appear, until many start-up cycles later. We first get foam rubber dust of filter, blowing through system. Then each start up cycle blows more dusty/sandy air downstream.

This dust damages S.A.I. system by contamination (sand being just one element of). Sand, also get into cylinder, rings and on valves seats and valve steams of exhaust valve. Then travel into CAT honeycomb passages.

 

[GuitarsandMopars]

I was getting a PO420 as a result of a bad 02 sensor gasket. The gasket is around $10. Plug your tailpipe with a rag and listen/feel for exhaust escaping around the sensors.

 

[RedMule]

Thank you all for the helpful suggestions! I'm really hoping to get to the bottom of this.

The SAI filter failure seems likely... or that some rodent bedding got in there and maybe fouled the CAT.

Just ordered a $30 borescope on Amazon, will take a look at the CAT when the O2 sensors are replaced.

Could someone point me to the Katacleen/high rev guidelines? I'm thinking it might be worth doing that protocol one last time.

Also, it seems Partsouq doesn't have any CATs for sale—and I tried to look it up on Impex but the Lexus part number didn't yield any results. What's the best resource for a new CAT, should that become a necessity?

 

[RedMule]

DTC may start at just one CAT. But will spread to other CAT and the S.A.I system eventually, when filter has failed. Not correcting will eventually take out the S.A.I system, engine and both CATs. About $23k ($4k S.A.I system, $15K engine and $4k CATs,) in damage, if all new replaced at Dealership. All due to, a tiny little filter failing!

The S.A.I. filter mod is a must have. Sooner or later ALL S.A.I. filter will fail. Either replace the $600 pump (blower) periodically, which houses the filter. Or mod to use an easily replaceable $20 motor cycle filter.

When filter fails. Will get various DTC (codes). The DTC typically will not appear, until many start-up cycles later. We first get foam rubber dust of filter, blowing through system. Then each start up cycle blows more dusty/sandy air downstream.

This dust damages S.A.I. system by contamination (sand being just one element of). Sand, also get into cylinder, rings and on valves seats and valve steams of exhaust valve. Then travel into CAT honeycomb passages.

I totally agree about your filter mod—kicking myself because the intake manifold was off just a week ago.

Where is the best spot to snake in the borescope to inspect the SAI blower?

 

[2001LC]

Thank you all for the helpful suggestions! I'm really hoping to get to the bottom of this.

The SAI filter failure seems likely... or that some rodent bedding got in there and maybe fouled the CAT.

Just ordered a $30 borescope on Amazon, will take a look at the CAT when the O2 sensors are replaced.

Could someone point me to the Katacleen/high rev guidelines? I'm thinking it might be worth doing that protocol one last time.

Also, it seems Partsouq doesn't have any CATs for sale—and I tried to look it up on Impex but the Lexus part number didn't yield any results. What's the best resource for a new CAT, should that become a necessity?

Cataclean, doesn't have a high rev procedure, that I know of.

High "REV" RPM runs (AKA Italian tune-up) or a host of names. Is simple running engine at high RPM under-load (driving). Which heats cylinders, valves, A/F & o2 sensors and CATS. In attempt, to cook off gunk and carbon deposit. It also has runs fuel through fuel injectors at max speed and volume. It's like turn your oven to clean cycle. The heat cooks oils and such to a white ash.

I'd only do short high RPM runs, if at all while Cataclean in the tank. I do it, just after using Cataclean or any of these CAT clean products. Which CAT specific products, are made up mostly of paint thinners/cleaners. If google cleaning CAT. You find videos on how, and see many are using paint thinners. But CataClean does have additional chemicals.

When doing a high RPM run (burn out). I start out with 15 drive on HWY, at normal RPM (A/T in D), Then take RPM up (A/T shift to lower gear) for a short duration of !3 minutes. The idea, is to take CAT temp for shorter duration at first. I case CAT have some unspent fuel. Thus, we reduce change of igniting CAT, burning them up. Also I want to hear & feel how engine handling the load.

Then once I feel all good for pushing engine higher & harder. With good oil and engine turned (no vacuum leaks and good oil). I get on the HWY shifting down so I'm running at about 4,500 RPM. I hold that RPM for ~3 minutes (Heating) Then shift to D, and run at normal RPM about 5 minutes (cooling). This gives CATs a chance to cool back down. Now I run at 4,500 for ~5 minutes, then cool down run. Then I run at 4,500 RPM for ~10, than cool down run. Doing these runs on the HWY, helps keep engine coolant temp in proper range.

I use a bluetooth connected OBDII device and iphone. This allows me to watch tech stream data. Like CAT temps, engine coolant (ECT), intake air temp, RPM, MPH, fuel trims (FT), etc. Long Term FT & ECT, I monitor more closely & often than most. I'm most interested in LTFT. While cruising on flat HWY, holding RPM & speed steady. Any change in vehicle attitude or throttle position, changes FT readings. So I'm looking for the points, within the logs, where perfectly steady. Long Term Fuel Trims (LTFT) tell us, what ECM is adjusting fuel trims too. To achieve or target FT of zero. Any reading over 5% is considered excessive.

Say we see LTFT of 3%. This means engine running slightly lean (more air than fuel). ECM adjust, so STFT (Short Term FT) ~0% (stoichiometric air/fuel mixture (14.7 parts of air to 1 part of fuel). A reading of 20% LTFT mean, we're running very lean, and ECM is working hard to get STFT to 0%. This could be vacuum leak or could be fuel starvation. A -20% LTFT, engines running rich. To much fuel dumped into CATs, can ignite and burn up them up.

The ECM is collecting Data from sensors (A/F, o2, MAF, ECT, TPS) to determine FT. If any sensor not function properly, data is corrupted. So each sensor must pass pre checks. Any sensor not passes set off a DTC. One I find that passes test, but not always optimal performance, is MAF.

I've read in mud, of CAT DTC being corrected be replacing o2. But personally. When I've seen CAT DTC, CAT has been bad. OR A/F/o2 DTC, those sensors were bad.
Exception has been either gunk-up: When a CAT or o2 loaded with unspent fuel, oil or gunk. Form either excessive idling (OM warns against), many cold start with very short drives never getting on HWY or engine malfunction dump fuel or oil into exhaust. In these the High RPM correct most every time.

Anyway, lets not go to fare down this rabbit today! hole.

Note:
I've found by watching CAT temp. Their temperature, max's at ~4,500 RPM. Running at high RPM may help blow more fuel through and "may" loosen some gunk & carbon, but will not create much more heat.

 

[2001LC]

I totally agree about your filter mod—kicking myself because the intake manifold was off just a week ago.

Where is the best spot to snake in the borescope to inspect the SAI blower?

I come in on side of throttle body. I've a overly flex 3' snake, with steerable 6mm camera. Once just past the SAI intake port (tube), I look back into tube.

Yellow line show the route I use with borescope snake camera. When intake manifold is not removed and SAI mod pipe (hose) is not attached, like they are in this picture.

Here borescope two pic, of S.A.I. filter still in place. This is what we want to see. If no filter, do mod ASAP. Eevery cold start-up, is damaging if filter missing.

 

[2001LC]

I'll repeat myself!
Having just a P0430, returning over many miles of engine run time. Is not likely a S.A.I. issue. With S.A.I. filter failure. We see P0420 & P0430 DTC, along with S.A.I. DTCs. All these DTC (codes) don't usually appear all at once. They may start as perhaps a P0430 DTC, perhaps an S.A.I DTC. But if we keep driving, in time we get all these DTC. You've driven for 2 years perhaps longer, but just one DTC?

How many miles since first DTC, include history of previous owners if you can. Also get all service history and look for reports of DTC (Codes, CEL).
Also look in history for engine issues: Coolant, intake, fuel, EVAP, MAF, Throttle body, etc. Anything more than just PM service or lack of. These are clues, that help paint a picture!

 

[RedMule]

I come in on side of throttle body. I've a overly flex 3' snake, with steerable 6mm camera. Once just past the SAI intake port (tube), I look back into tube.

View attachment 3600342View attachment 3600343
Yellow line show the route I use with borescope snake camera. When intake manifold is not removed and SAI mod pipe (hose) is not attached, like they are in this picture.
View attachment 3600344
Here borescope two pic, of S.A.I. filter still in place. This is what we want to see. If no filter, do mod ASAP. Eevery cold start-up, is damaging if filter missing.

View attachment 3600345View attachment 3600366

This is SOOOO incredibly helpful, thank you!!

I just bought this on Amazon, looks like it will get the job done, yes?

Amazon.com

 

[2001LC]

This is SOOOO incredibly helpful, thank you!!

I just bought this on Amazon, looks like it will get the job done, yes?

Amazon.com

That snake camera should work very well. My 360* snake camera, 3' snake is to flexible. So I run it through a ~2' long tube, to help guide it.

 

[RedMule]

That snake camera should work very well. My 360* snake camera, 3' snake is to flexible. So I run it through a ~2' long tube, to help guide it.

My first few attempts weren't successful, I may have to try the tube to help me. Don't have the knack of it yet.

If I do have to replace the CAT, got any suggestions on buying one for CA? Just checked PartSouq and Impex, no luck. What's next best option for a new one?

 

[2001LC]

Getting in just the right spot, then looking back into S.A.I. inlet tube. Takes, time and patient to get the shot.

CA like CO has strict laws, which some aftermarkets manufactures can't or don't care ($) to certify for.

I used a Davico CAT, because a shop had already install one on the other side. Few years late CO changed it's laws, so Davico no longer would sell into CO. Yet one guy I know, purchased a set of Davico CAT's through Amazon. He said, Amazon sellers, don't care where they send. Two things I like about Davico CAT. Bolt in and has a small heat shield on top.
You can take to a CAT shop and have then install aftermarket or call one or two, and see what they use.

Also be mindful, you'll like find two OEM part numbers for each side. One with heat shields one without. I've only been able to purchases without.

I've also purchased OEM form Toyota Dealership. I like Genuine Toyota Parts and Accessories: Official Online Store Serra Toyota of Decatur - https://autoparts.toyotaofdecatur.com/ the best when buying online. They re-pack parts, and do a better job than anyone one the world. Even radiators and FDS arrive undamaged. Wait and watch for 20% or even 25% off everyday wholesale prices, they had two last year. Free shipping over $75. Better then Partsouq or Impex.

BTW: Last I checked with Toyota Dealerships parts dep. Heat shields are NOL (no longer available). But, I saw a set of Tundra 4.7L VVT CATs at local Toyota parts dep other day. They had heat shields on them. I'm going to see if I can get a set of their heat shields. To see if they fit our CATs. They looked the same! It's not required to have heat shield. But, upper helps reduce heat transfer to cabin. Lower reduce risk of starting grass fire, when off-road.

 

[RedMule]

I'll repeat myself!
Having just a P0430, returning over many miles of engine run time. Is not likely a S.A.I. issue. With S.A.I. filter failure. We see P0420 & P0430 DTC, along with S.A.I. DTCs. All these DTC (codes) don't usually appear all at once. They may start as perhaps a P0430 DTC, perhaps an S.A.I DTC. But if we keep driving, in time we get all these DTC. You've driven for 2 years perhaps longer, but just one DTC?

How many miles since first DTC, include history of previous owners if you can. Also get all service history and look for reports of DTC (Codes, CEL).
Also look in history for engine issues: Coolant, intake, fuel, EVAP, MAF, Throttle body, etc. Anything more than just PM service or lack of. These are clues, that help paint a picture!

I will do this. Just reinstalled Techstream on my new laptop, will get as much data as I can for you.

BTW: Last I checked with Toyota Dealerships parts dep. Heat shields are NOL (no longer available). But, I saw a set of Tundra 4.7L VVT CATs at local Toyota parts dep other day. They had heat shields on them. I'm going to see if I can get a set of their heat shields. To see if they fit our CATs. They looked the same! It's not required to have heat shield. But, upper helps reduce heat transfer to cabin. Lower reduce risk of starting grass fire, when off-road.

This would be great, please let me know.

I think I read somewhere that Magnaflow is about to release a CA compliant CAT for the 100 Series, but I don't see it on their site.

Can anyone recommend a CAT shop in the northern LA area?