P0420 and P0430 - 2006 LC (1 Viewer)

[jerryb]

if a toyota mechanic looked at that he'd say you're fine. -+35 will get you a code, vvti.
IT's better if you watch wideband and narrow band o2 sensor voltage, considering you have a 420. It still could be a random occurrence. If it happens repeatedly then it's probably real.
Watching all four voltages, then you'll have info to swap sides (if you can) see a dead one. See a stagnant one reading hi/lo etc

 

[white_lx]

I keep getting a P0420. I clear the code and it returns the same day. Attached is some info i pulled my my cheap code reader. Something looks off. Anybody want to translate that into layman's terms for me?

Long term fuel trims are a bit high - but nothing too crazy. Photo shows +7% trims at ~1500 rpm. How are the numbers at idle and at 3000 rpm? Do they get better with higher RPM? Then you have a vacuum leak. If they get worse then it probably is a dirty MAF (or maybe even a dirty air cleaner filter).

The picture you shared does not have enough information to diagnose the P0420. For that you need to monitor the four oxygen sensors as per post #361.

 

[Baumer06]

2006 LC100 here with 271K miles on it. Just went through a Secondary Air Injection headache. Got that fixed and now I’m throwing a P0420 & P0430 code. I’ve changed the air filter, PVC, and both O2 sensors with no luck.

I’d second the request for additional information on the URD 4.7 O2 bi-pass. Any information on the correct model to get for the LC100, where it clips into the O2 sensor harness, and configuration/settings would be extremely appreciated.

 

[jerryb]

Can be located second page on the 100 forum right now. Edit, 3rd page

here.

 

[2001LC]

2006 LC100 here with 271K miles on it. Just went through a Secondary Air Injection headache. Got that fixed and now I’m throwing a P0420 & P0430 code. I’ve changed the air filter, PVC, and both O2 sensors with no luck.

I’d second the request for additional information on the URD 4.7 O2 bi-pass. Any information on the correct model to get for the LC100, where it clips into the O2 sensor harness, and configuration/settings would be extremely appreciated.

What A.I. codes did you have, prompting you to fix Secondary Air Injection? What was done?

It's possible, your 2ndary switch A.I. issues is related. I'll be exploring this possibly soon.

 

[farright]

Magnaflow is supposed to be coming out with direct replacements for the 2006 and 2007 100 series fairly soon from what i read...

 

[looking4lc]

What A.I. codes did you have, prompting you to fix Secondary Air Injection? What was done?

It's possible, your 2ndary switch A.I. issues is related. I'll be exploring this possibly soon.

any update?

 

[2001LC]

No. I'll not have time to work on my stuff until this winter. Words gotten around, that I work on 100 series. So list of locals' rigs keeping me too busy.

If anyone with this issue past or present. Has all code (DTC) pending or active, that were found with or about same time as P0420 & P0430, could list them?
That would be helpful.

 

[2001LC]

For those that have read this far and missed the edit in post #2.

I did come up with what IMHO. Is the leaning cause of the 100 series 06-07 4.7L 2UZ-fe VVT CAT P0420 & P0430 failures.

IMHO they will all fail, if not modified.

I've came up with a theory, of what's damaging the CATs. Worked to prove out. Then a solution!

I tested this on a 2007 w/reoccurring P0430 & P0420. It's been more than 2 years since I modified this 07, with a perfectly street legal modification. It has work perfectly. IMHO all Toyota/Lexus with the Secondary Air Injection (S.A.I.) system, which was introduced in most after 2005, to meet environmental laws. Will fail if not dealt with.

You can read about it and how to modify to correct, in the below thread.

S.A.I. Filter Modification, in VVT engines. To prevent its failure! Alert Alert!

We've a $2.00 part in the S.A.I. (secondary air injection) system of the VVT engine, that is taking-out ~$7,000.00 $15,000 $25,000 (inflation) in parts. WOW! I've a very easy and cheap WORK AROUND. You are going to love this ;) This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the...

forum.ih8mud.com

 

[jerryb]

You're that bored?

 

[planomateo]

You're that bored?

I appreciate his persistence on this.

 

[2001LC]

You're that bored?

Nope. Just saw that I'd not updated since 2020, when asked.

So update: Found cause, came up with solution, tested and works without issue. No more P0430 or P0420 or S.A.I. DTC, and street legal.

 

[2007landcruiserWA]

I have a 07 LC w/85K on it. Had recent work done to it at the shop and within 5 miles the same codes came up for me

P0420 and P0430​

Work I had done (By shop):

• Replaced alternator
• Replace air filter (it was there so why not)
• Replace all coolant hoses and coolant

My question, would any of the above work compromise any area that would throw the P0420 or P0430 code? It's ironic that as I am driving it from the shop that these codes went off (never had any issues with fuel, etc. The car is babied. I called the shop and they said its unrelated and a coincidence. After reading this thread, before I go down a rabbit hole trying to figure out the issue, I want to see if anyone else has a similar issue happen or if you think the shop could have inadvertently done something that would cause those codes?

For additional context, at 77K I had a full tune up at toyota, trans fluid change, front/rear axle lube changed, transfer case fluid service, P/S flush, water pump/timing belt replacement, replaced thermostat, replaced serpentine belt, Repl P/S rack, All joint boots, and new brakes (yes, it was $7k!)

Thank you for your help

 

[Andrew S]

I have a 2007 LC as well. Grade and brand of fuel, as well as climate, and idle/warm up times, all seem to be causes of those codes in my case. The previous owner never had problems, but used mid-grade fuel all the time. I had nothing but intermittent codes not long after I bought the car. They would usually clear within a hundred miles, but would reoccur eventually. I finally gave up and installed sensor extensions on the downstream sensors, which solved the issue.

Maybe the dealer filled your fuel tank with a different brand or grade of fuel? I'd use up the fuel that's in the tank first, fill with your usual and burn through that tank. That might be all it takes.

 

[Import Driver]

I have a 07 LC w/85K on it. Had recent work done to it at the shop and within 5 miles the same codes came up for me

P0420 and P0430​

Work I had done (By shop):

• Replaced alternator
• Replace air filter (it was there so why not)
• Replace all coolant hoses and coolant

My question, would any of the above work compromise any area that would throw the P0420 or P0430 code? It's ironic that as I am driving it from the shop that these codes went off (never had any issues with fuel, etc. The car is babied. I called the shop and they said its unrelated and a coincidence. After reading this thread, before I go down a rabbit hole trying to figure out the issue, I want to see if anyone else has a similar issue happen or if you think the shop could have inadvertently done something that would cause those codes?

For additional context, at 77K I had a full tune up at toyota, trans fluid change, front/rear axle lube changed, transfer case fluid service, P/S flush, water pump/timing belt replacement, replaced thermostat, replaced serpentine belt, Repl P/S rack, All joint boots, and new brakes (yes, it was $7k!)

Thank you for your help

I had the P0430 code awhile back. Replaced the right 02 sensor and it went away. Two weeks ago it came back. I cleared the code almost immediately and it has not returned. It it comes on again I may install a sensor extension.

Check your gas cap as well (as silly as that seems). Clear the codes and see what happens. Since you have both codes its highly unlikely the cats are bad IMO. Probably something simple.

 

[2001LC]

I have a 07 LC w/85K on it. Had recent work done to it at the shop and within 5 miles the same codes came up for me

P0420 and P0430​

Work I had done (By shop):

• Replaced alternator
• Replace air filter (it was there so why not)
• Replace all coolant hoses and coolant

My question, would any of the above work compromise any area that would throw the P0420 or P0430 code? It's ironic that as I am driving it from the shop that these codes went off (never had any issues with fuel, etc. The car is babied. I called the shop and they said its unrelated and a coincidence. After reading this thread, before I go down a rabbit hole trying to figure out the issue, I want to see if anyone else has a similar issue happen or if you think the shop could have inadvertently done something that would cause those codes?

For additional context, at 77K I had a full tune up at toyota, trans fluid change, front/rear axle lube changed, transfer case fluid service, P/S flush, water pump/timing belt replacement, replaced thermostat, replaced serpentine belt, Repl P/S rack, All joint boots, and new brakes (yes, it was $7k!)

Thank you for your help

Those services have nothing to do with CAT DTC P0420 & P0430, by themselves. But there are common issues during those services, that may be contributors to CAT DTC.

1. Prolonged idling.
2. Vacuum lines left off, damaged or lose.
3. Low coolant level in radiator. Check, by parking with front end higher than rear overnight. Check under cap after 8 hour cool down, before sun-up. Check reservoir level and that its hose free of obstruction and goes straight down to bottom of reservoir.
4. Make sure air pipe to throttle body and filter rubber seal seat properly.

Toyota recommends against, prolonged idling. As it can damage CATS. Most times, a high RPM drive or just driving on HWY. Cooks-off the CATs, A/F & O2 sensors well enough. But keep-up prolonged idling, and over time they can be damaging.

The 06-07, have the S.A.I. system. Which I've written about and link above and will link here again. If a VVT engine has both CATs indicating (DTC) below threshold. I would not only look at engine coolant system, tune and prolonged idling as with all 4.7L. I'd also look at the, S.A.I. filter.

S.A.I. Filter Modification, in VVT engines. To prevent its failure! Alert Alert!

We've a $2.00 part in the S.A.I. (secondary air injection) system of the VVT engine, that is taking-out ~$7,000.00 $15,000 $25,000 (inflation) in parts. WOW! I've a very easy and cheap WORK AROUND. You are going to love this ;) This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the...

forum.ih8mud.com

 

[lekjart]

Jumping on this threadnaught just to get some perspective. I have a 2003 4.7 UZJ100 that has about 185K miles. I previously had a p0156 code and replaced that sensor and it went away. I then have had p0420 coming up sporadically. Just out of curiosity I bought an OBDII reader and started recording O2 sensors (both upstream and downstream). Did a 10 minute drive with car already heated and had the following results. Sensor 1 on both banks looks normal, but the Sensor 2 and bank 1 is definitely more noisy than bank 2. Also, for both, the average voltage seems pretty low compared to what I have seen with others on this thread. Could that be because of different year of car? How would you interpret both of these graphs.

Bank 1

Bank 2:

I plan to do a few of the things recommended on this thread before actually considering exchanging cat, but I do have one extraneous symptom which is unusually high fuel consumption, but apart from this car runs relatively smooth.

 

[2001LC]

o2 don't go bad often, on their own. But happens, and usually just one. If two (Toyota Denso or Denso) go bad, something is more than likely taking them out, loading them up or it's the CAT. I always look to see if a reason, can be found. Such as mud on o2 and wiring. Even grease, mud, water, crud, etc. in wire housing. or something in how engine operation.

If CAT indeed bad. Again look for the why.
Prolong idling.
MAF sensor is a leading cause.
Bad compression.
Coolant leak into combustion chamber.
Exhaust leak before or at 02.
Vacuum leaks.
Engine coolant temp.