Replaced oxygen sensor, now have a P0430 code

[pinnacle]

Replaced oxygen sensor, now have a P0430 code


I had a P0051 error code on my '03 94,000 mile Tundra so over the weekend, I replaced the front passenger side oxygen sensor with a new Denso. The install went fine.

The next day, the engine light came on again. Now, the error code is a P0430 - catalyst efficiency below threshold (bank 2). I read through these forums to get some ideas. Some people in previous posts suggested getting a can of CRC MAF sensor cleaner and cleaning the MAF sensor. I did so and cleared the error. The error came back less than ten miles later. As long as I was in the neighborhood, I swapped out my air filter too.

Some people have said that this is a common problem when non-Denso oxygen sensors are used. I did use Denso, so I'm thinking maybe I have a bad one. I sent an e-mail to Rock Auto tonight to see about getting it replaced. I'm hoping that will take care of it but I am thinking ahead in case it does not.

Some people have said that oxygen sensors tend to all fail about the same time. I have not yet received error codes for the other three. Despite that, is it possible that they could be having some affect on all of this? I hate to replace them now if I do not have to but I probably could.

Some people have suggested a bad catalytic converter but it seems like just as many suggested that is bad advice. I hope so because a bad cat would be too expensive.

Any ideas? Thanks.

[Highwaylizard]

Originally Posted by pinnacle

Replaced oxygen sensor, now have a P0430 code


I had a P0051 error code on my '03 94,000 mile Tundra so over the weekend, I replaced the front passenger side oxygen sensor with a new Denso. The install went fine.

The next day, the engine light came on again. Now, the error code is a P0430 - catalyst efficiency below threshold (bank 2). I read through these forums to get some ideas. Some people in previous posts suggested getting a can of CRC MAF sensor cleaner and cleaning the MAF sensor. I did so and cleared the error. The error came back less than ten miles later. As long as I was in the neighborhood, I swapped out my air filter too.

Some people have said that this is a common problem when non-Denso oxygen sensors are used. I did use Denso, so I'm thinking maybe I have a bad one. I sent an e-mail to Rock Auto tonight to see about getting it replaced. I'm hoping that will take care of it but I am thinking ahead in case it does not.

Some people have said that oxygen sensors tend to all fail about the same time. I have not yet received error codes for the other three. Despite that, is it possible that they could be having some affect on all of this? I hate to replace them now if I do not have to but I probably could.

Some people have suggested a bad catalytic converter but it seems like just as many suggested that is bad advice. I hope so because a bad cat would be too expensive.

Any ideas? Thanks.

I had three O2 sensors fail within a thousand miles of each other. The fourth one went about twenty thousand miles after the other three. Not sure on the history of the sensors or when they were replaced as I bought the truck used. It is true that O2 sensors tend to go like women go to the bathroom - in groups.

I also had a catalytic convertor go bad - driver's side. Replacement by the dealership was over a thousand bucks:

Failed Cat Cause Poor MPG?

You may be able to get by with an aftermarket catalytic convertor but you had better do some serious in depth research backed up by some rock solid evidence that the aftermarket cats are reliable. No sense in putting something in there that may throw codes or fail prematurely.

Good luck in getting this figured out and keep us posted on what happens.

[duffyatkinson]

This is exactly how these systems seem to fail in a cascade. Your upstream fuel-air sensor (BXS1) was operating at less and less efficiency until it failed altogether. Now that you have replaced it with a new unit operating right at specs, the ECU is finding an imbalance with the results now being reported from the downstream, after-cat oxygen sensor (BXS2).

The remedy: replace the downstream sensor with the appropriate Denso unit. That's about $65 and 20 minutes of your time. (Don't forget to also replace both the mounting nuts as well as the metallic gasket. Don't reuse these parts.)

The downstream unit looks like this:

[bill3508]

You really should always replace o2 sensors in pairs. Not doing so just causes an imbalance in the signals received especially with that high a mileage.

[pinnacle]

Thanks everyone. Rock Auto agreed to replace the original one. It got roughed up a little during shipping because they used an envelope instead of a box so even if it is not the real problem, I'm better off replacing it. Also, I ordered a new rear passenger side oxygen sensor and a gasket. When it all gets here, am I going to need some kind of sealent for the gasket?

[bill3508]

When I say replace in pairs I mean two front sensors. They control your air/fuel, rears don't do anything other than monitor catalytic converter efficiency. Your signals are probably going to be very different between your new front passenger o2 and the one with all the miles on it.

[pinnacle]

Originally Posted by bill3508

When I say replace in pairs I mean two front sensors. They control your air/fuel, rears don't do anything other than monitor catalytic converter efficiency. Your signals are probably going to be very different between your new front passenger o2 and the one with all the miles on it.

Oops. Based on what duffyatkinson said, I thought you meant the two on the passenger side.

I guess I might as well just replace all four then. From what I have read on this forum, I am probably living on borrowed time for the others anyway. Time to place another order (driver's side front and driver's side rear).


When I install the rear sensors, will I need a sealent for the gasket?

[bill3508]

Originally Posted by pinnacle

Oops. Based on what duffyatkinson said, I thought you meant the two on the passenger side.

I guess I might as well just replace all four then. From what I have read on this forum, I am probably living on borrowed time for the others anyway. Time to place another order (driver's side front and driver's side rear).


When I install the rear sensors, will I need a sealent for the gasket?

You only need some anti-seize to put on the threads. Make sure you don't get any on the sensor itself. No sealant for the gasket should be needed. I was just making the comment that is just a good idea to always replace both the fronts when one fails if the other has a good bit of miles on it. That way you keep your engine working as good as it can.

[400exboy2]

how does a cat fail? I dont really know or never expericed it myself. Im running jba headers right to super 40's with no cats.

[duffyatkinson]

Originally Posted by 400exboy2

how does a cat fail? I dont really know or never expericed it myself. Im running jba headers right to super 40's with no cats.

Catalytic converters fail for one of two reasons: direct, blunt-force damage, or internal breakdown caused by running caustic additives in the fuel stream and/or a fuel-air mixture out of whack. A bottle of Techron every six months or so isn't going to hurt anything, but continually dumping bottle after bottle of god-knows-what into your tank is asking for a steep cat replacement bill.

[MrBeanley]

Stupid Question Time: I thought there was a warranty of 80,000 or 100,000 or something on the "emissions system" on this rigs. Wouldn't the O2 sensors and/or the cats be covered under that warranty?

</stupid_question>

[pinnacle]

Originally Posted by duffyatkinson

. . . The remedy: replace the downstream sensor with the appropriate Denso unit. That's about $65 and 20 minutes of your time. (Don't forget to also replace both the mounting nuts as well as the metallic gasket. Don't reuse these parts.)

The downstream unit looks like this:

Do you know what size nuts are on the rear oxygen sensors? It's sunny today so I thought I would start on the removal even though the parts will not be here till later. The nuts are extremely rusty. I just hope the bolts are still okay once I get the nuts off.

[400exboy2]

allright thanks i understand now. Thank god for living in West Virginia where there is no emissions. And also thank god for o2 simulators that will let the truck run right with no cats.

[duffyatkinson]

Originally Posted by pinnacle

Do you know what size nuts are on the rear oxygen sensors? It's sunny today so I thought I would start on the removal even though the parts will not be here till later. The nuts are extremely rusty. I just hope the bolts are still okay once I get the nuts off.

I don't recall offhand, because it is a specialty nut. I haven't had to replace mine; I have zero rust/corrosion on the underside. The dealer is the best place to pick them up. Don't forget the oval metal gasket as well.

[longwoodklon]

Originally Posted by MrBeanley

Stupid Question Time: I thought there was a warranty of 80,000 or 100,000 or something on the "emissions system" on this rigs. Wouldn't the O2 sensors and/or the cats be covered under that warranty?

</stupid_question>

Good point. Many years ago Toyota sent out a notice to all early Tundra owners that this is the case. I had already replaced my O2 sensors (on my dime). I sent them the receipt and they sent me a check. Since original poster has an '03 I don't think they will help him.

<clip from another thread>
-----------------------------------------------------
to see if your vehicle is covered. You can call the Toyota Customer Experience Center at 1-888-270-9371 Monday through Friday, 5:00 am to 9:30 pm, Saturday and Sunday 7:00 am through 3:00 pm Pacific Standard Time.

2000 Through Mid-2002 Model Year Tundra V8 (2UZ-FE Engine) Oxygen Sensor Warranty Enhancement Notice
2000 Through Mid-2002 Model Year Toyota Tundra V8 (2UZ-FE Engine). In recent months, Toyota has received reports of custome concerns regarding the two oxygen sensors located in the exhuast manifolds that monitor exhaust emissions. These oxygen sensors are installed ahead of the catalytic converter and are also known as the Number 1 Oxygen Sensors. To minimize these concers, Toyota will extend the warranty of these oxygen sensors for illumination of Malfunction Indicator Lamp (check engine light) related to any of the following diagnostic codes (as diagnosed by your local Toyota Dealer): PO135 and P0155.

If your check engine light illuminates, please bring your vehicle into your local Toyota dealer for diagnosis and repair. Please note that a check engine light can illuminate for unrelated to the Number 1 Oxygen Sensors.

This warranty extension is offered for a total period of 7 years or 90,000 miles from the vehicle's in-service date, whichever occurs first, for the failure of eiher of the Number 1 Oxygen Sensors. The specific components covered by this warranty extension are:
- Number 1 Oxygen Sensor, Bank 1 (left side exhaust manifold)
- Number 1 Oxygen Sensor, Bank 2 (right side exhaust manifold)
This offer is limited to your specfic Tundra whose VIN is provided and is subject to the same conditions set forth in the New Vehicle Limited Warranty section of your Owner's Warranty Information booklet*, with the exception of the extended warranty coverage on the oxygen sensors listed above. Please note that this coverage is for warranty work performed at an authorized Toyota dealer only.
-------------------------
/Mike