Replaced oxygen sensor, now have a P0430 code

[pinnacle]

All the parts are now here. I replaced the front passenger side ox sensor again (the previous one had been abused during shipping so I did not trust it). After installing the replacement, I cleared the error and it lasted about 30 miles before the engine light returned with a 430 error.

Next, I intend on replacing the rear passenger side ox sensor. I'm not entirely sure yet how I am going to get the old one off without destroying the bolts. It is very rusty. The replacement nuts I got from Toyota are 12mm. If the nuts currently on my truck were ever 12mm, they are not anymore. They might be 9 or 10. 10 slips, 9 barely gets on. I have sprayed a lot of Liquid Wrench under there so hopefully that will help. I also have a nut splitter but I think it may be too big to fit over the nuts. I will figure all this out the next day it stops raining.

[jamesjr4750]

Originally Posted by pinnacle

All the parts are now here. I replaced the front passenger side ox sensor again (the previous one had been abused during shipping so I did not trust it). After installing the replacement, I cleared the error and it lasted about 30 miles before the engine light returned with a 430 error.

Next, I intend on replacing the rear passenger side ox sensor. I'm not entirely sure yet how I am going to get the old one off without destroying the bolts. It is very rusty. The replacement nuts I got from Toyota are 12mm. If the nuts currently on my truck were ever 12mm, they are not anymore. They might be 9 or 10. 10 slips, 9 barely gets on. I have sprayed a lot of Liquid Wrench under there so hopefully that will help. I also have a nut splitter but I think it may be too big to fit over the nuts. I will figure all this out the next day it stops raining.

P0430 isn't the sensor , its the CAT , low flow if I remember when mine showed up. I just ended up clearing the codes like 15 times over a period of a week and hard driving and it went away. Do some Jackrabbit starts, and then some high speed run puttin a "Load" on the engine for awhile on straight aways at night with no one around and blow those catalytic converters free of their debris that are choking them up. Cures the problem. Seriously. Did with mine. Haven't had the code show back up for over a year.

[duffyatkinson]

Originally Posted by jamesjr4750

P0430 isn't the sensor, its the CAT...

Wildly presumptive at best. Especially considering the OP posted that he is in the middle of O2 sensor replacement. New units upstream can very well cause the ECU to dislike the data coming from the older downstream units. It doesn't mean that the cats are underfunctioning.

And what "debris" are you referring to when you suggested running WOT to "clean out"??

Point is, wouldn't you rather find that you can solve the problem for $90 rather than dumping $1,400 on a new cat and finding it was the sensor all along?

[redmanronnie]

I had the P0430 code and it turned out to be a simple fix.
A code P0430 may mean that one or more of the following has happened:

• The catalytic converter is no longer functioning properly
• An oxygen sensor is not reading (functioning) properly
• There is an exhaust leak <--my problem

An exhaust repair tech found a crack in the pipe just above the drivers side converter. He used a 4' piece of garden hose and listened to one end and ran the other end over the welds at both ends of converter and upstream until he located a crack under the heat shield. A 5 minute weld fixed my problem. Hope this helps.

[jamesjr4750]

Originally Posted by duffyatkinson

Wildly presumptive at best. Especially considering the OP posted that he is in the middle of O2 sensor replacement. New units upstream can very well cause the ECU to dislike the data coming from the older downstream units. It doesn't mean that the cats are underfunctioning.

And what "debris" are you referring to when you suggested running WOT to "clean out"??

Point is, wouldn't you rather find that you can solve the problem for $90 rather than dumping $1,400 on a new cat and finding it was the sensor all along?

P0430 Catalyst System Efficiency Below Threshold (Bank 2) . To me that indicated: I needed to flow more exhaust through there and more heat build-up since I was granny driving around too much. So different driving habits / methods were enacted before even thinking of buying new 02 sensor(s) , and last on my mind a NEW CAT converter from Toyota. Even though those all crossed my mind thus fueling the problem.

Also , there are debris that collect/gunk up all along the honeycomb walls on both ends of the CATS. Seen it personally, close-up upon inspection when taking the entire exhaust system off recently when installing JBA headers and a TRD supercharger soon after having the code being thrown.

I was only passing on my own personal observation of what cured getting rid of the P0430 code (on my truck) without buying new 02 sensors anywhere downstream or upstream. Or CATS. Like I said it kept coming back over and over being cleared with a Scan-gauge II during normal driving: 60-65mph @ night (3:00 am) going back home from work over a period of 2 weeks. So my take was something definately HAD to have cleaned / blown out/burned off/out immediately after the higher constant speeds-slowdowns and higher RPM ( Higher temperature EGT's; constant higher exhaust gases flowing through-out the entire exhaust system at much higher rates/temps will burn off collected debris: Like a hotter fire burning the subjected fuel source like wood for instance to an ash much faster ) driving and higher RPM's because the code went away and has never come back. The ECU fuse was pulled for 24 hrs and the negative terminal battery connection was disconnected as well. No code(s) have ever shown up. Truck has 90K miles on it.

[5 Speed]

I have thrown this code over the years and always reset it with my Scangauge. I don't believe it is the cats because I have had two smog tests and they are perfect, the lowest in the range so before replacing an expensive cat I might get a smog test to see the cats efficiency.

[pinnacle]

I replaced the rear passenger side oxygen sensor last week and cleared the code. Within 10 miles, the P0430 code had returned. Over the weekend, I went out of town. Just prior to getting on the highway, I cleared the code. For the next 90 miles (going 60-75 mph) the code did not return. Once I reached my destination and returned to stop and go driving, the P0430 code quickly returned. Somewhere I read once that the "computer" in my truck stores data on my driving history. On a hunch, I decided to disconnect my battery to delete this. My thinking was that maybe my problem was solved but it was just taking awhile for the new correct data to average out with the old bad data. My hunch did not work out. For the entire 90 miles home, the code did not return but once I resumed stop and go driving, the P0430 error returned. At this point, I am assuming my passenger side cat is failing.

On to the driver's side. Knowing that these oxygen sensors tend to fail around the same time for people and winter is coming, I decided to just go ahead and replace the driver's side sensors. Today, I replaced the driver's side rear and now I have a P0133 code. Ugh!!! Tomorrow is supposed to be another nice day so I plan on replacing the driver's side front oxygen sensor. Could there be a difference between the Densor OEM sensors from Rock Auto and the Denso sensors from Toyota? I was under the impression they were the exact same thing but this project is not going as well as I hoped it would.

[duffyatkinson]

Hmmm. Okay, it's either one of three things:

1. You have installed the improper model Denso sensor unit
2. You have an exhaust leak somewhere between the manifold/exhaust flange and the cat, or
3. You really do have a problem with the cat.

I would go to extra lengths to eliminate without a doubt that it isn't a sensor issue. I'd also double-check the correct part usage if Rockauto.com is the only reference you used to buy the unit.

A couple of questions:

1. What model number BXS1 did you install? What model number BXS2 did you install?
2. Upon visual inspection, is there any apparent damage to either of the cat assemblies?
3. How much (if any) fuel additive do you normally/ever run through your fuel system? If any, what type and when?

** NOTE: 100,000 miles is the expected life of the heated fuel/air & oxygen sensors used in our trucks.

[pinnacle]

This morning I decided to exchange the rear driver's side oxygen sensor with the new one I installed on the rear passenger's side. Since I have a 2WD Tundra, both rear oxygen sensor are the same part. I wanted to see if the P0133 error would follow the sensor over to the other side. For no particular reason, I decided to check the engine error codes again before I started. The P0430 code is still there, but the P0133 error code is gone. I'm not sure what to think about that. When I installed the driver's side rear oxygen sensor, I heard it click into place so I was sure I did not have a loose connection, but I checked anyway. It is most definately securely attached. Since the P0133 error code is gone, I did not flip/flop the rear ox sensors.

I checked around between the manifold and the rear sensors to see if I had any rust holes or cracks. Everything appears to be solid.

I have never used a fuel additive in my truck.

I double-checked Rock Auto with DensoAfterMarket.com to confirm I have the right parts. Both sites agree with each other. Since I have a 2WD Tundra, both front ox sensors are the same model part and both rear ox sensors are the same model part.

Front = 234-4169
Rear = 234-4161

It's dry again today so I am going to pro-actively swap out the driver's side front ox sensor.

Thanks everyone for all your input.

[Boxer]

I recently replaced my rear driver side O2 sensor and starting immediately throwing P0430 code, I then replaced the rear passenger side O2 sensor ... cleared the code and it hasn't appeared again. I used Denso sensors, first tried a Bosch but had to remove because it threw codes.

[buglao]

what about wires connections?. make sure they're right and well connected. this is just another thing to look into.

[duffyatkinson]

Originally Posted by buglao

what about wires connections?. make sure they're right and well connected. this is just another thing to look into.

yep. you should hear/feel the tactile "click" when the connectors are properly seated. if you don't, unplug it and reseat.

[RacerX0232]

I had an issue with my 05 Tundra. The dealership said that both the two upstream o2 sensors were bad. So i replaced them and ended up with an $800 bill. A month later down the road check engine light again with the same two codes; Bank 1 and Bank 2 too rich and it gave the same codes as the prior time whenever they hooked it up to their computer at the Toyota garage. I called the dealer and they didnt really know what could cause them to go bad. Here to find out my neighbor who owns a small service station had the problem with his tacoma. When running a cold air intake the oil you spray on the filter gummed up my MAF causing it to have false readings which then tripped by computer displaying those two codes. After three intense cleanings of the MAF Sensor, Air Filter, and my Throttle Body I am 6,000 miles later with no codes and no problems.

[pinnacle]

Originally Posted by RacerX0232

I had an issue with my 05 Tundra. The dealership said that both the two upstream o2 sensors were bad. So i replaced them and ended up with an $800 bill. A month later down the road check engine light again with the same two codes; Bank 1 and Bank 2 too rich and it gave the same codes as the prior time whenever they hooked it up to their computer at the Toyota garage. I called the dealer and they didnt really know what could cause them to go bad. Here to find out my neighbor who owns a small service station had the problem with his tacoma. When running a cold air intake the oil you spray on the filter gummed up my MAF causing it to have false readings which then tripped by computer displaying those two codes. After three intense cleanings of the MAF Sensor, Air Filter, and my Throttle Body I am 6,000 miles later with no codes and no problems.

I cleaned the MAF sensor and replaced my air filter but I did not do anything to the throttle body. I can take a look at that.

The P0133 error returned on the driver's side so today I exchanged the new rear sensor on the driver's side with the new rear sensor on the passenger's side to see if the error follows the part. I did not drive the truck again today after I did that so I will find out tomorrow what the results are. I still have not replaced the front driver's side sensor. I have not got it to budge yet. My can of Liquid Wrench is pretty old so I thought maybe it has lost its potency. I went and got a new can of PB Blaster and have sprayed that on a few times so far.

I can not help but wonder if it was a good idea to get these Denso O2 sensors. It certainly seems like they would be the same exact thing as Toyota sells but without the Toyota name stamped on the side but I am starting to wonder. I'm having way too many problems on this project.

Thanks again everyone.