P0420 and P0430 - 2006 LC

[KYLandy]

Just wanted to add that I changed my rear O2 sensors last Sunday. I originally replaced the old, warped sensors with the non-OEM universal style and I had to splice wires and all that crap. I began to doubt my electrical wiring skills and decided to order the 234-4260 OEM sensors. Last Sunday, I installed the OEM ones which included the connectors (no splicing) and I have not had a check engine light since. The P0420 still shows up as pending but does not trigger the MIL. I did not reset the computer by disconnecting the battery after I installed the OEM sensors but no MIL light, yet. I am right on the threshold, though, of failing. It appears that my cat efficiency test does not fail every single time but only intermittently and if the test does not fail using the 2-trip detection logic, then the MIL will NOT come on.

The entire troubleshooting procedure for these codes from the 2006 FSM is attached to this post. Very detailed and explains a lot.

Here's the pending cat efficiency results:

 

[tacoduck]

quick question, if my VSC and traction control light is on due to an emissions issue, does that mean its no longer working? that seems like a huge liability for mr T. lets say I'm driving down the freeway and make an evasive maneuver and flip my truck because the VSC isn't working, then I would be super pissed at lexus. traction control has virtually eliminated SUV rollover crashes, and to disable it due to an emission issues seems punitive.

 

[ikanclim]

Short version: To finally find resolution, I replaced both Cats with Magnaflow units and both O2 sensors with the Amazon-Denso units. While the unit was up on the rack I went ahead and had the shop cut out the rusty muffler / resonator and replace it with a mild Magnaflow stainless muffler. With the new muffler I significantly reduced heat in the second row floorboard, gained a little sound, cut ~50 lbs from the system, and improved clearance at the rear with the new tail pipe ending just above the bottom of my ARB pig. . The original exhaust routing exited below the rear bumper for a little while. After a few steep descents, the tail pipe was naturally relocated with a new profile... The end result: The vehicle runs better than it ever has in the 2 years that I have owned it. I gained 2-3 mpg on the highway - city unchanged, acceleration is greatly improved, and the engine "just runs better" with the less restrictive system.

Part numbers used in the end:
Qty 2 O2 Sensors - Denso 234-4260 - $130.00

Exhaust system revamp - $770.00 out the door
Qty 2 Catalytic Converts - Magnaflow 99354HM
Qty 1 Muffler - Magnaflow 13235
2 new mid-pipe sections, same Y-pipe, new pipe / routing configuration from muffler to exit

Long story on how I got into the mess:

I apologize in advance if I repeat anything in this thread as I have not read every post, but feel certain that I have lived the same nightmare as the OP.

This past Thanksgiving night I lost my alternator on Interstate 85 just outside of Charlotte, NC. I have 190K on the 2006. Failure was immediate - heard bearing whine while at highway speed, lost voltage on gauge, and shortly thereafter the battery was depleted. I have an Optima Blue Top as a secondary and introduced it to the system with the 200A continuous duty solenoid used in the isolation circuit. This allowed me a few more miles but ended up on the side of the road with 0 power. I knew better than to push it but I was so close to the next exit I took the chance but lost in the end. AAA took care of me and had a local company pick up the cruiser that night, store it on their lot, and deliver it to my home in Greenville, SC the next morning.

I replaced the alternator with a Denso reman unit sourced from a local parts house and I was off....so I thought. I heard a rattle in the right Cat and had both 20 & 30 codes with MIL. I went through the same clearing, monitoring, testing....with TS and saw similar results as the OP. I looked for vacuum leaks, replaced the PCV, checked plugs, and cleaned the O2 sensors (in the Cat - left the AFR units alone) with no change in results. With the new rattle in the right Cat i can only assume I dumped some fuel into the Cats when I lost ignition, caused detonation, and "blew" apart the Cat.

I talked to a few performance shops in the area about alternatives to spending $$$$ for OEM Cats and while most said that Toyota's are a real pain when dealing with aftermarket Cats - apparently the OEM units are built better than most, are extremely efficient, and as a result, the ECU programming is tight and allows very little tolerance.

I found a shop that offered to replace both Cats with Magnaflow units and guarantee no MIL with proper system operation with a 100% refund with removal of the aftermarket parts allowing the OEM install. I figured I had nothing to lose and gave it a shot.

After cutting out the OEM units, the right Cat was in fact destroyed. No light passed through the unit and after punching the screen out of the exit, several pieces dumped out. The left unit, while not physically damaged, would not pass light and looked obstructed as compared to the new, higher flowing units.

I went ahead and replaced the muffler / resonator with a single Magnaflow muffler along with the Cats. I also replaced both O2 sensors at the same time. The sound of the new system is mild, but sounds like a V8 at startup / acceleration without a drone at highway speeds. Overall I am very pleased with the new system. The cruiser runs better than it has in the 2 years I have owned it with 2-3 mpg better highway economy, better, smoother acceleration, and the butt dyno says I freed up a few HP with the higher flowing system.

I have put ~1500 miles on the system in the last month with no MIL / Pending codes and and overall better driving experience. While I am a firm believer in using OEM parts, the cost of OEM in this case was several thousand dollars and just did not make sense in my opinion. Time will tell if the system performs as expected and keeps the ECU happy. I hope so but even if I have to replace the Cats 3 more times I am still shy of the total cost of the OEM job... A gamble I am willing to take.

Good luck with your journey and hopefully you will remain in the clear with the sensor replacement. If not, keep in mind aftermarket catalytic converters as an option to restore the efficiency the ECU is looking for. Let me know if you want to see any current TS data or have any questions around my experience.

-David

 

[KYLandy]

I would love to see the results of your latest catalyst efficiency test. It's obvious that it is passing the test but by how much? Any solution that works is a good solution, IMHO. I am open to alternatives and I really appreciate you sharing your experiences. What was your final cost for the Magnaflow system?

 

[Colorado80]

I think the cost stated by @ikanclim was $770. I checked on the cats and the amazon pricing was ~$90 for each cat and ~$65 for the muffler.

I too would be interested on the response to @KYLandy question above.

Thanks

 

[ikanclim]

I will perform the test in the morning and post the results. If anyone sees anything questionable please let me know!

Thanks
dj

 

[ikanclim]

 

[ikanclim]

Data list attached as well for reference.

 

[KYLandy]

Data list attached as well for reference.

Thanks for doing that! Very impressive results on the cat efficiency test! Looks like this is a real solution. I presume that you had to fabricate the pipes to add the cats, right? Did you use the ends of the OEM pipes or fabricate something else?

 

[KYLandy]

Also, I know this is a lot to ask, but I would love to hear the sound of it at idle and on the highway. Do you find it annoying or pleasant?

 

[ikanclim]

Thanks for doing that! Very impressive results on the cat efficiency test! Looks like this is a real solution. I presume that you had to fabricate the pipes to add the cats, right? Did you use the ends of the OEM pipes or fabricate something else?

Yellow: Maintained
Red: Replaced with new components / pipe

Coming off of the headers I maintained the original flange / studs. Looking at them, I figured on breaking 50% and did not see any real benefit in removing them given I was not doing a factory replacement. The exhaust system is well built and the original pipe was in great shape. We cut a few small sections to fit the new catalytic converters in the gap where the originals were. The new units were a little shorter than the OEM units. Standard exhaust work here using saw, pipe expander to overlap the oringal pipe, and mig welder.

I left the y-pipe in place and cut the muffler out just beyond the B1/B2 union. We fabbed a small piece to mate the Magnaflow muffler to the original pipe. Nothing fancy, expanded the pipe and welded the joints.

Exiting the muffler we bent (a few times with a little wasted pipe) a new section to run the original route with just a little more clearance over the rear axle housing and a higher exit point so the bumper takes the beating, not the tail pipe. All original hangers were reused and the system is mounted as solid as the factory system. Just a lot less under there now.

I figured I lost the "cruiser" aspect of the 100 when I added OME bits, roof rack, AT tires, ARB F&R bumpers...not a handful to drive at all but no longer a "cruiser". The new system is a little louder but nothing like a Flowmaster. More along the lines of the Borla system, just without the beautiful, mandrel bent SS tubing...

I will grab a few sound clips from startup, idle, and highway driving and attach them in a day or so.

Thanks
dj

 

[KYLandy]

Yellow: Maintained
Red: Replaced with new components / pipe

Coming off of the headers I maintained the original flange / studs. Looking at them, I figured on breaking 50% and did not see any real benefit in removing them given I was not doing a factory replacement. The exhaust system is well built and the original pipe was in great shape. We cut a few small sections to fit the new catalytic converters in the gap where the originals were. The new units were a little shorter than the OEM units. Standard exhaust work here using saw, pipe expander to overlap the oringal pipe, and mig welder.

I left the y-pipe in place and cut the muffler out just beyond the B1/B2 union. We fabbed a small piece to mate the Magnaflow muffler to the original pipe. Nothing fancy, expanded the pipe and welded the joints.

Exiting the muffler we bent (a few times with a little wasted pipe) a new section to run the original route with just a little more clearance over the rear axle housing and a higher exit point so the bumper takes the beating, not the tail pipe. All original hangers were reused and the system is mounted as solid as the factory system. Just a lot less under there now.

I figured I lost the "cruiser" aspect of the 100 when I added OME bits, roof rack, AT tires, ARB F&R bumpers...not a handful to drive at all but no longer a "cruiser". The new system is a little louder but nothing like a Flowmaster. More along the lines of the Borla system, just without the beautiful, mandrel bent SS tubing...

I will grab a few sound clips from startup, idle, and highway driving and attach them in a day or so.

Thanks
dj

Perfect! Thanks for the detail!

 

[RECRUISER]

This is to KYLandy.
Make sure you fix your exhaust leak first! I had a very nice 2006 Lexus and it was throwing all kinds of check engine lights. It did have an exhaust leak. And it leaked behind the cat. The dealer looked at the error codes and said I needed new catalytic converter's for $4200.
Instead, I spent $50 repairing the exhaust leak and all my codes disappeared and never came back! It surprised me that you could throw error codes with an exhaust leak behind the cats but it does cause an issue and I know this is a fact from personal experience. Chances are for 50 bucks you could clear your codes as well and never look back. I am in Paducah hope this helps, but from experience do not ignore the exhaust leaks!

 

[KYLandy]

This is to KYLandy.
Make sure you fix your exhaust leak first! I had a very nice 2006 Lexus and it was throwing all kinds of check engine lights. It did have an exhaust leak. And it leaked behind the cat. The dealer looked at the error codes and said I needed new catalytic converter's for $4200.
Instead, I spent $50 repairing the exhaust leak and all my codes disappeared and never came back! It surprised me that you could throw error codes with an exhaust leak behind the cats but it does cause an issue and I know this is a fact from personal experience. Chances are for 50 bucks you could clear your codes as well and never look back. I am in Paducah hope this helps, but from experience do not ignore the exhaust leaks!

Exhaust leak is fixed but codes still return. Ran some Cataclean through it and it made no improvements in the test results. In fact, seems to have made it worse. I may have a small head gasket leak. I lose the tiniest bit of anti-freeze in the reservoir over several months. I'm watching it closely to see if I lose anymore. I topped off the reservoir and will be monitoring it closely. It does not leak any antifreeze so that's why I suspect a head gasket. Runs fine and no discoloration in tailpipe but a small leak overtime would definitely ruin the cats. Can't replace them until I know for sure. Might need to pressure test the radiator to confirm but I don't have the tools to do it.

 

[RECRUISER]

I was curious about your posts because I JUST bought a 2003 land cruiser with 190,000 miles in excellent condition and got it home this week (Feb 2017) and the first thing the check engine light came on ( P0420 & P0430 ) with the VSC TRAC & VSC OFF as well. Previous owner more than likely reset the codes and sold it to me without telling me.
However it has been well maintained otherwise at Oxmoor Toyota dealership in Louisville with a ton of service records all its life and is in incredibly good condition otherwise. So I am starting my journey on this. And I have read the entire thread along with several other related threads as well.
These codes seem incredibly hard to diagnose. I have absolutely a incredibly smooth Idle and no loss of power, no hesitation etc.
My cats have been replaced with aftermarket ones at some point. One of the last dealership service records from November 2016 (just 2 months ago at this writing) noted this aftermarket cat replacement in the service report along with the P0420 & P0430 codes.

So apparently this vehicle has been throwing these codes for a while and a previous owner replaced the cats and that did not prove to be the problem as many owners who went to the trouble and considerable expense to replace the CATS with no improvement have found out.

So I am going to look upstream at the PCV and spark plugs and good solid ground from the battery terminals, throttle body cleaning, vacuum hose leaks etc.

Please keep this thread alive and update as I will be monitoring this thread and I will do the same if I make any progress.

I have a snap on Solus which should be able to read oxygen sensor efficiency etc. and hopefully give me some further direction on what appears to be a very difficult problem to resolve.

 

[2001LC]

Test of coolant system pressure or cylinder leak down test is a good idea. I'd be amazed, unless engine has overheated you'd have a leak at head IMHO.

I found a small coolant leak on the 07 I just bought. What caused the leak at 172K IDK. I'm going through maintenance history to see if indication of being removed.

It's at the front water by-pass joint on PS. The fronts are easier to detect then rears are. The leak appears to be more if not only when engine cold, I'm still watching to see. It so small it would be missed during most inspections. This 07 has red in it possible aftermarket or Toyota IDK, it was done at Dealer records show SLL which it's not.

I noticed reservoir low when cold, and so I checked the radiator. Thinking, it may have not been top properly as was only a pint or less low.

Then I found upper hose had old leak at some point just a bit, but dry.

I kept looking, finding the actual leak.

Looking at rear by-pass, they look good but are very hard to see.

 

[KYLandy]

I have checked my overflow tank at cold temps each time because I know the system will draw from the overflow tank when it cools down when it creates a vacuum in the cooling system. I could be worried about nothing here but, as I have said before, I don't want to replace them til I know why they went bad. Unfortunately, I can't just remove them and look at the catalyst material due to the their design and position in the pipe. Honestly, I don't think the head gaskets are bad, but I am grabbing at straws here. I have several options, including buying used cats from cruiserparts.net, or putting in these: Underdog Racing Development

Haven't decided which approach I am going to take. We don't have vehicle emissions testing here in Louisville so the URD O2 sensors might just buy me some peace of mind. I can't tell you how many times I have cleared the P0420 code. Hundreds!

 

[RECRUISER]

Today I changed the spark plugs which looked like they had been in there for a long long time. I also took the PCV valve out and it was really dirty gunked up and was not closing all the way. I cleaned the PCV valve and reinstalled and ordered a new one from the dealership for nine dollars and put The old One back in and until the new one comes in at the dealership. I believe PCV was causing a problem because I could blow through it both ways since it was so dirty and it looked like it had been in for a looooong loooong time. After cleaning it only allowed air to flow one way instead of two ways before I cleaned it. Thirdly I cleaned the throttlebody which looked very dirty. I also ordered an air filter which should be in tomorrow February 14th 2017.
I put everything back together and drove it and so far the codes have not returned but I've only put about 100 miles on it today and combination city and highway driving. It is very possible they will come back on but I know for sure that the maintenance that I did on it today was needed badly and All the parts I put all will help performance and gas mileage at the very least. I will Keep everybody updated on my progress as I get a few more miles on the vehicle.

I am encouraged here that I have had half a day of driving and no return of the check engine lights. Two days ago when I cleared the codes with my snap on Solus they returned within about 20 minutes. Today I removed the negative battery terminal for the two hours worth of work I did on it changing spark plugs and cleaning the PCV valve and cleaning the throttlebody. So that was one important difference today, I removed the negative battery terminal instead of resetting with the scan tool. So I haven't been able to compare apples to apples yet because I cleared the codes in two different ways and/ however I am getting different results so far, the maintenance that I did is the only new variable that was added today.

 

[RECRUISER]

Here is my Snap On Scan tool message before I started researching. So many times it proves NOT to be the Cats, and so many videos out there that point you in the upstream direction such as spark plugs, PCV, dirty throttle body, dirty MAF sensor, air filter, proper ground.
A dirty running engine can tend to overwhelm the cats? Hope this proves to be true, and my Cats haven't been trashed in the meantime.

 

[RECRUISER]

Very interesting update today. As mentioned in previous post above my PCV was completely fouled and not closing properly and I had both P0420 & P0430 codes.
After cleaning PCV (and changing spark plugs, cleaning MAF, & cleaning throttle body) I drove 100 miles without any check engine lights returning and when they did return I just had the P0430. This was a deviation from 20 miles until codes returned from the day prior. Encouraging!

Well after that hundred miles the p0420 also came back on as well but the pattern was different so I was encouraged by what I had done with the PCV valve.
So today I took the PCV valve out today again and it was not closing fully again so I cleaned it again today and put it back in and drove for most of the day and ONLY the P0430 came back on. The PO420 has completely disappeared and isn't even pending status which is a significant deviation from the normal pattern of both codes popping up together. And this time the only thing I did differently was address the PCV valve again. I have a new one on order from the dealership OEM and when it comes in I will quit messing with the used one and start fresh.

MY TAKEAWAYS TODAY:

1. Isn't it reasonable to question what the odds are of both banks of catalytic converters failing at the same time?!? Or are the Cats still good and is something else to blame?

2. Shouldnt this make us ask the question of what is going on upstream that is overwhelming the cats over a period of time? And, if fixed could the codes start to clear up?

3. My pattern of throwing codes is changing with attention to the PCV. My advice is if you have changed your PCV valve, and your Codes return within 100 miles pop it back out and see if it has got gunked up again like mine did after 100 miles. If so take it back out and clean it again pop it back in and overtime hopefully the top of your motor will clean out where your PCV won't clog up and your codes disappear.

To KYLandy I remember you saying that you put in some cleaner and the problem got worse. Maybe you were starting to move some crud around and need to continue cleaning until you get the junk that started moving cleaned out. Food for thought.