P0420 and P0430 - 2006 LC (9 Viewers)

[KYLandy]

Connected Techstream and monitored AFR, coolant temps, O2 sensor voltage and everything else. I don't know what each data point means but many of them are obvious. It looks like the new O2 sensor voltages are within range. I am planning to run the A/F Control test to see if the sensors are fluctuating wildly under lean/rich conditions. If you see something, please draw my attention to it.

 

[KYLandy]

Here's a larger image:

 

[Julian Stead]

Your 02S B1S2 voltage is low.

 

[KYLandy]

I found this on Toyota Tech Info Site:

If I am reading this right, if the downstream O2 sensors flucuate wildly while the upstream A/F sensors fluctuate between 3.0V and 3.5V (normal) then the cats are deteriorated.

I still want to run the Control the Injection Volume Test when I get home tonight to be certain, but it looks like my cats really are bad, at least the driver's side is bad (Bank 1?).

I am having problems with my Techstream software. I had been using the "Evaluate" version but it stopped offering me that option last night. The serial # I was given isn't being accepted by Techstream so I don't know if I can get it working again.

 

[bctlex]

I am just throwing this out there. I used to have an 01 Sequoia. It had this same error code (either 420 or 430) and it disable VSC. I had replaced the O2 sensors, plugs. It did not fix the the problem. The CEL will come back on, and off randomly. Took it to the dealer, according to them it is because there is a crack on exhaust manifold which screw up the computer reading the data. I know on mine the exhaust manifold has a crack - I can hear it making ticking sound. We sold the car without fixing it. Again, not that this your problem, but maybe it is one more thing to check before replacing cats, which is very expensive.

 

[Julian Stead]

Your fuel trims look good, I would swap the o2 sensors to see if the lower voltage moves with the sensor.

 

[Colorado80]

Swapped downstream sensors and the voltage stayed with the bank and did not move with the sensor. Vacuum leaks check by spraying carb cleaner with the engine cover off and no rpm changes. No exhaust leaks either. Any other suggestions?

 

[Julian Stead]

Check the wiring connections, make sure there is no voltage drop in the cables itself.

 

[KYLandy]

On Friday, I ran the injector volume test and monitored the O2 sensors. Everything worked fine and it did not set any DTC codes. The test enriches and leans the mixture so you can test the sensors and everything was in range. When I turned off the test and let everything settle back in, I got the following readings. the sensors showed 0.74 and 0.76 which shows that the catalyst efficiency is normal. There has to be some sort of spurious problem that is setting the DTC codes. I'll keep driving it until the codes show up again and then check the freeze frames which should capture the readings at the time the code was set.I am still not convinced that my cats are bad.

 

[Julian Stead]

If your Cats where bad the voltages would be fluctuating, so I would rule that out anyway. Your voltages are good at present so maybe it is good now.

 

[KYLandy]

One thing I have noticed is that there is a bit of a stumble upon acceleration from a dead stop. If I don't ease into it, it feels as if there is a slight clunk in the drive train before acceleration. Could be u-joints or something in the TPS or APPS causing this. I'm not sure if it is related, but I am going to keep testing until I figure out what it is. I'm not sure what the voltages and settings should be so I'll need to read up on them.

Might just go ahead and change the spark plugs which are due at 120k, anyway. It currently has 114k on the odometer.

 

[Chance]

Unfortunately not everyone has included year, make, model and mods to their signature....... "HINT"...

It seem each 100 series in this thread with same codes are either 2006 or 07. This indicates a year specific issue. Possible pointing to timing or air pump, which are most apparent difference I can think of. One other issue I don't think we've touch on is fuel quality. Low octant, alternatives fuel (ethanol and such) added to gasoline should also be considered.

@Chance, PCV valve usually just need a good cleaning with solvent. The PCV hoses (DS & PS) do however go bad around 100K (7yr) and should be replaced. Good idea to double check all vacuum lines while at it.

@KYLandy, Hopefully someone experienced with tech stream will help with your question.

Business end of your "warped" o2's look pretty normal, but with just a little more white then I'd like to see. I'd think such high heat internally as to warp external part, business would have looked very different. Something like this:

View attachment 1353060

Thanks for the advice, I going to pull the pcv valve and clean it this weekend along with changing out the hoses. I'll have to read up on how to check for a vacuum leak. Again, I appreciate all the help.

 

[KYLandy]

I keep feeling like I am hijacking this thread but since I am having the same problem, I hope my contributions are helpful. Please tell me if they are not.

So, I got the DTC codes P0420 and P0430 again last night. Only P0420 is current with P0430 pending. I connected to Techstream and pulled up the freeze frame data which is captured at the time slightly before and after the DTC code is set. It's not looking good. Both the O2 B1S2 and B2S2 sensors show wild fluctuations such as what is depicted in the waveform chart above. There are 4 pages of data that are captured at the time the DTC codes are set and this is just one page. I have looked for concurrent conditions that might indicate an engine problem rather than a catalyst problem but I don't see anything and don't understand all of the data points. If anyone knows where I can get a description of each data point, please let me know. I can't find anything in the Techstream application that explains each metric in detail. I may have to to buy some time online at techinfo.toyota.com in order to fully understand what each parameter is and what it is measuring.

If anyone sees anything that is out of spec, other than the O2 voltages, please let me know. At this point, I might change spark plugs just to be sure but if the spark plugs were bad, I would expect the AFR sensors to report that. The upstream AFR sensors seem to be in spec throughout the event (3.0-3.5V). When I ran the Control Injection Volume test, I suspect that I did not heat up the catalytic converters to a high enough temperature before testing. They need to be at a certain temperature before the problem shows up. During this event, the downstream O2 sensors were between 1110.6F and 1114.2F. I believe that these temperatures are computed so they aren't actual temperatures but I probably did not have them up to temp before testing.

 

[KYLandy]

I took the data above and graphed it so I could analyze the problem. In this case, only P0420 was current and existing while P0430 is still pending. The lower threshold for the downstream O2S is 0.15V and for the upstream AFR sensor the lower threshold is 3.0V. If, during the monitoring, the voltage drops below that level, a DTC code will set. Looking at the bottom chart, you can see that the AFR voltage for B1S1 dropped below 3.0V but no code was triggered for that error. In the top chart, you can see that the O2S B1S2 dropped below 0.15V immediately before the AFR B1S1 dropped below 3.0V. I don;t know if this is the system reacting to O2S B1S2 and adjusting the AF Ratio or what. Any ideas?

 

[2001LC]

I'm surprise we're not seeing more members' input here!

 

[KYLandy]

My goal in analyzing the data was to determine if I need to replace the upstream sensors before I replace the cats to see if that helps. The O2S B1S2 threshold breach occurred BEFORE the AFR B1S1 threshold breach so it seems to me that the AFR breach was an "adjustment" in response to the preceding event. If so, what caused the O2S breach? it might simply be that the cats ARE bad. But, we are talking about $1,800 per catalyst to replace them with OEM parts. But, as has been demonstrated early on in this thread, replacing the cats might not fix the problem. I don't want to spend the money if it isn't going to fix this. I NEED TO KNOW IF THE PROBLEM IS REALLY THE CATS!

Even if I replace spark plugs, PCV valve, gas cap and various other parts, it would still cost less than buying new cats. I am really hoping that the data can tell me what happened so I can zero in on the exact problem and fix it.

Edit: Also, I am looking for WHY the cats are bad, if that is the case. If I replace the cats without knowing, it will just happen again.

 

[Colorado80]

@KYLandy You are not hijacking this thread at all. I am hoping that once this is solved we can help others that may encounter this in the future.

 

[Julian Stead]

sorry before I start as I have given you abit of bad info, I have never tested a af sensor, I thought it was just a different name for a upstream o2 sensor, but have found out to what the differences are. Toyota af sensors run almost flat at 3.3 volts, they don't produce voltage like a traditional 02 sensor but gets it from the ECM, The ECM needs to be reset after changing this type of sensor due to the ECM pairing with the old sensor, the ECM reads the current from the sensor and keeps it as close to 0 amps as it can, as this is Lambda1. Your downstream 02's are way off though, was everything up to temp?

 

[Julian Stead]

Ps, @Chance has 02 upstream sensors and @KYLandy has AF upstream sensors, must of had a change in type at one stage.

 

[KYLandy]

Ps, @Chance has 02 upstream sensors and @KYLandy has AF upstream sensors, must of had a change in type at one stage.

That is an important distinction that I was not aware of. I knew mine we AF sensors but not that @Chance was different.