P0420 and P0430 - 2006 LC (3 Viewers)

[Colorado80]

Hi Everyone,

I have been on mud for quite some time and hardly ever post because normally whatever issue/issues I have come across in the past I have found a resolution on mud. However, I have these codes (P0420 and P0430) popping up which are for Cat Efficiency both bank 1 and 2 and really haven't found a definitive resolution. Furthermore, I was headed up to Breckenridge from Denver (Read: Higher Elevation) and the truck died on me. There was no strong gasoline odor which is normally attributed to charcoal canister. That problem normally has been attributed to a near-death fuel pump which I plan on replacing soon.

Here are the things I have done so far after doing some research:

• New Toyota Gas cap
• B1S1/S2 + B2S1/S2 O2 sensors have good readings and are moving as they should (scan tool=Solus)
• Havent detected any misfires on the scan tool (over two days of data logging)
• Cleaned MAF

Now here are the questions that I have for you folks:

1. Should I change spark plugs (Denso SK20R11)?
2. Should this be attributed to the fuel pump fiasco resulting in lean conditions?
3. What am I missing here?
4. Could it be that the windshield is leaking onto the ECU and causing this? (The truck runs beautifully otherwise)

What say ye?

 

[2001LC]

I've not looked at what your code's symptom tree, just what you've stated.

Often times the cats' will indicate malfunction because they're not reaching operating temp. Running cooler will also affect air fuel ratio as ECU thinks engine still not at temp. First place I'd look is at thermostat. Quick test is turn on cabin heater, does blow very hot on cold morning, it should.

Edited: 12/19/21:
We've many upstream issues that can cause a CAT to go bad. When both CAT codes. P0420 BK1, AND P0430 BK2 coming up at same or near same time. This indicates something upstream both banks of engine, rather than just one BK (bank). With perhaps one exception, something getting into tailpipe. Either clogging exhaust pipe like a rodent nest. Or worst, water flooding all the way into CATs.

The VVT engine in the 100 series from 2006-2007, is the one we see both codes come up the most. I've come up with a possible cause and solution, related only to the VVT 4.7L engine. Which MAY affect every 4.7L VVT engine.

S.A.I. Modification in VVT engines to prevent its failure! Alert Alert

We've a $2.00 part in the S.A.I.S. of the VVT engine, 1s taking-out ~$7,000.00 $15,000 (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 2006 & 2007 100 series Land Cruiser & Lexus...

forum.ih8mud.com

 

[a_traut_man]

Just curious what elevation do you live at? I noticed when I lived 5500'+ I would get the same light and the same codes but when I moved closer to sea level the codes went away and my truck smogged as everything fully operational... I haven't had the issue since moving out of Colorado and closer to sea level

 

[Colorado80]

@2001LC The timing belt was done along with water pump thermostat etc @150k. Currently has 171 on the LC. It is a 2006
@Traut100 I think you maybe on to something; This was from the bay area (eastbay - san ramon). Never had an issue in CA. Over the last two years in CO and it just started popping up.

 

[Colorado80]

Just an update:

Got the cats replaced and the lights came on within 30 minutes. . . Any other suggestions?

 

[cwininger]

^dang. that's a lot of spendy for no worky. did you go with oem cats?

 

[2001LC]

Hope you kept the old cats, OEM are the best, pricy and rarely go bad. Too have both CATS go bad at same time is a million to one shot.

What's your MPG and has it changed (do you have a heavy or lite foot on gas pedal)??

Just because you had new thermostat installed 21K ago, doesn't mean it was installed properly (jiggle valve up), or has/is been functioning properly. Both CATS reading malfunctioning at same time, indicates something upstream (include rear o2's) not working as designed. Most likely this condition has been present for some time. Did you check thermostat, level of coolant, flow of coolant in radiator, pressure test system & temp sensor function or did you just assume it is all good?

If coolant system checks out then move on to air/fuel mixture. If mixture to rich (to much fuel to amount of air) it will run cooler. The ECM uses input from sensors to adjust fuel mixture. Going up in elevation, air becomes thinner and external pressure (barometric pressure) drops. Engine may "flood" a condition of to much fuel in mixture. Bad data such as from o2's can cause this, but highly unlikely both left & right side o2's going bad at same time and without DTC.

Some more consideration:

Exhaust leak between heads & CATS can also cause bad data. This would be loud tick sound, that will not go away once operating temp reached in most cases.

In 06-07 series 100 used an air induction pump. Some thing I know nothing about, but given your model year may be worth a read.
06/07 Air Induction Pump Failure & Bypass

The 06-07 4.7 VVti uses oil pressure to operate camshaft timing control valve along with date the ECM receives from Coolant temp sensor, VVT sensors', TPS, MAF, Vehicle speed signal & Crankshaft position sensor.

Tip:
Always disconnect battery for 30 minutes while (before & during) cleaning MAF to reset ECM and help protect against shorting.

Hi Everyone,

*****
Now here are the questions that I have for you folks:

1. Should I change spark plugs (Denso SK20R11)?
2. Should this be attributed to the fuel pump fiasco resulting in lean conditions?
3. What am I missing here?
4. Could it be that the windshield is leaking onto the ECU and causing this? (The truck runs beautifully otherwise)

What say ye?

1. Never hurts to inspect plugs. Condition and gap can be a revealing clue.
2. CATS rarely give malfunction code form running hot (lean AFR)
3. ?, the FSM perhaps.
4. I've not seen this type of issue from water leak, but you never know. Dry out, if problem goes away then you'll know. As dry as weather has been unless you've washed it should have dried already. Try keeping dry and in sun with windows down as much as possible for next week or two.

 

[Julian Stead]

Just my 2 cents, the only thing that checks CAT efficiency are your down stream oxy sensors, if your readings are good on these sensors then you wouldn't get these codes. The easiest way to check the cats would of been to check the exhaust emmisions, if you are getting lamda 1 then I would of rechecked the downstream oxy sensors as it would be safe to presume the cats are good. The voltage on the downstream oxy sensors will start to mimic the upstream sensors signal if the cats where bad. If you get a steady reading but its below 0.6 you are getting to much oxygen leaving the CAT, check exhaust leaks, vacuum leaks, upstream oxysensors. Coolant kills cats and oxy sensors so make sure the coolant system is working correctly.

 

[tacoduck]

subbed for outcome...

 

[looking4lc]

Just my 2 cents, the only thing that checks CAT efficiency are your down stream oxy sensors, if your readings are good on these sensors then you wouldn't get these codes. The easiest way to check the cats would of been to check the exhaust emmisions, if you are getting lamda 1 then I would of rechecked the downstream oxy sensors as it would be safe to presume the cats are good. The voltage on the downstream oxy sensors will start to mimic the upstream sensors signal if the cats where bad. If you get a steady reading but its below 0.6 you are getting to much oxygen leaving the CAT, check exhaust leaks, vacuum leaks, upstream oxysensors. Coolant kills cats and oxy sensors so make sure the coolant system is working correctly.

Hi Julian,

how is the coolant kills cats?

i have code p0430 and it seems like Bank 2, 1 and Bank 1, 1 not working ( in OBDII) i get 0 V

i also have minor leak on top of the radiator which i am plan to fix soon.

 

[Julian Stead]

If your coolant gets into the exhaust system, say through the head gasket then it can damage the cats and lambda's. As long as your not losing water and the system isn't pressurising then you should be ok. Maybe your obdii reader doesn't read the upstream voltage as this should be fluctuating from 0.1 to 0.9 volts. You can use a multimeter to double check if in doubt. What are the downstream sensors reading.

 

[looking4lc]

Here

If your coolant gets into the exhaust system, say through the head gasket then it can damage the cats and lambda's. As long as your not losing water and the system isn't pressurising then you should be ok. Maybe your obdii reader doesn't read the upstream voltage as this should be fluctuating from 0.1 to 0.9 volts. You can use a multimeter to double check if in doubt. What are the downstream sensors reading.

here is a pic of my obdII reading Voltage as follow: Bank 1 S1 , Bank 1 S2
Bank2 S1 , Bank 2 S2

 

[looking4lc]

Above clearly shows (1,1) and (2,1) are defective and need to be replaced, am I correct?

 

[Colorado80]

No resolution yet. Just checking back in . . . Here is the plan of attack:

1. Techstream
2. Change plugs
3. Change O2 sensor (depending upon what techstream says)

I'll keep all posted with updates as I dive in this weekend.

 

[michaelharrisco]

For what it is worth...I replaced both O2 sensors on our old 4runner when I had a very similar situation and it fixed everything. My suggestion is to spend the money to either get them from the dealer or at a minimum get the Denso sensors. The cheapos are finicky and a pain to deal with.

I'd do this change out before any other steps you are thinking about taking. The codes and the issue you describe are just like what I dealt with and O2 sensors did the trick and the CEL never came back on for the rest of the time we owned it (i.e. ~75k miles after O2 sensors).

 

[Chance]

I have an 07 LX with the same codes. I have all 4 new denso sensors to replace Monday on my post-call day off . I'll let you know if it clears my codes. I did the AIP bypass bc the dealer I bought the LX from seemed to think that was the issue and had already purchased the kit. I installed it and no change, so I'm moving to the O2 sensors next. I'll keep you posted

 

[looking4lc]

apparently front Sensors called " Air Fuel Ration" Sensor and not O2 Sensor. went today to replace the front and i bought the wrong items. Sucks

Denso part # 234-9051 for lx 07

and i got 234-4260 , does anyone know what this is for? i know they are O2 sensors but are they for the one in the back?

if i can use them in the future i dont need to return them since i live overseas.

Thanks

 

[looking4lc]

Here is the one I removed

 

[looking4lc]

And here is the one I bought.

Denso 234-4260 Oxygen Sensor https://www.amazon.com/dp/B00199FBQY/ref=cm_sw_r_cp_api_.tCfybVCBHPT3

 

[Julian Stead]

I am not sure of the part numbers, they are all o2 sensors but the front ones are part of the fuel strategy, and the rear ones are for cat efficiency. For your front ones to not be functioning and the truck to still be driveable then I would imagine the fuel system is staying open loop, which means it is ignoring the upstream oxy sensor signals. The system will stay open loop if the temps don't rise enough, so again I would double check your coolant system and make sure there are no air locks and that the engine temp sensor is reading good.

The color of your old sensor looks contaminated, what color coolant are you using as it looks green, or have you been using a fuel additive. Sensors normally fail and stick at a voltage around 0.450v so I would look a little deeper into it.