O2 sensor question

Hi - my 04 Tundra started making some noise today like there was an exhaust leak right under my drivers seat all of a sudden. Check engine light is on too.

Taking a look, the O2 sensor behind the catalytic converter has a rotted gasket, and more alarmingly, no nuts on the two bolts that holds the sensor and guard in place, which was allowing for the exhaust to escape and resulting in the noise and (I'm assuming) the check engine light.

Assuming the sensor might need replaced judging by the wiring there, but I need to replace the gasket and nuts as well obviously.

Can anyone tell me the part numbers for the sensor and gasket, and tell me what size bolts those are? Seems like an easy enough fix but I want to make sure I get the right parts online.

Thanks!

 

What is the code#?

 

Dunno - haven't been to get it scanned

 

You need either:

manfiter OBD2 Scanner Car Code Reader Turn Off Check Engine Light Read & Erase Fault Codes View Freeze Frame Data I/M Readiness CAN Diagnostic Scan Tool for All OBD II Protocol Cars Since 1996

https://www.amazon.com/Manfiter-Upg...&keywords=odb2+scanner&qid=1586129365&sr=8-37

Or go better with either the android or apple version of Torque app ($5) using one of these:

$15 Veepeak Mini Bluetooth OBD II Scanner Auto Check Engine Light Code Reader Car OBD Diagnostic Scan Tool for Android (Incompatible with iOS)

https://www.amazon.com/Veepeak-Blue...&keywords=odb2+scanner&qid=1586129487&sr=8-39

But yeah autozone and all do it for free. I like the Torque app, besides reading & resetting odb2 codes, it provides a load of information about the engine and transmission. Luck.

 

Zooming in shows it to be a Denso 89465-0C120 which is what I used recently when changing mine on a 2004. I bought mine from local yokel Napa dealer which came with gaskets. Given one of the nuts was messed upped, I chose to also buy a pkg of exhaust nuts that also came with studs. Should be able to purchase at any auto type parts store....Napa, Autozone, Adavance Auto etc.

 

Why does that matter?

With any exhaust leak you are getting a code.

New gasket, new nuts and reassemble. If you get on this right away you won't need to buy a new O2 sensor.

 

My thoughts too.... Had to order parts but they will be in on Thursday. We'll see how it goes. The studs are rusted, but I'm hoping the nuts will still fit on correctly since it doesn't look like you can just buy the flange with the studs without also having to weld it on (there is a place online that sells this as a "kit" but I don't have the equipment to do it that way).

 

I have a 2002 tundra.i have replaced mine. Write down that number for a comparison, go to the denso website and look it up and compare numbers. Also you can call them for technical help, they are very helpful and will advise your. Hope this helps

 

Ah man you lost your nuts..........how's that happen. O2 might not be bad, but since your there I would put a new one in, should come with gasket. Spray the studs with some PB blaster and wire brush the threads and see if you get some new nuts on there. Common metric size, 6mm or 8mm, hard to tell from pick. Hopefully you can, if not, might have to run a Die over them. Good Luck.

 

I did find a reference suggesting these were 1.25 x 8mm so we'll see how that goes! Thanks!

 

Sounds about right, factory nuts would use a 12mm socket aftermarket might be 13mm socket........6mm nuts would take a 10mm socket.

 

You can always take the new ones to Napa and get a rethreading die to chase the threads.

 

Somebody mentioned OBDII scanners earlier. I wanted to throw out BlueDriver (www.bluedriver.com ) as an option. I bought one last December and the things are pretty great, especially for $99. They also handle ABS/SRS codes.

 

Code readers are really stepping up their game. Lots of power for decent prices now days.

Anyone that wants to maintain their own vehicle should have one.

 

CHECK OUT MY THREAD

ENGINE CODE P0430 DIAGNOSTIC HELP

 

Truthfully, I was expecting the entire thread to be in all caps. ...and I was actually mildly disappointed that it wasn't

 

@20Tundra04 Did you ever get this fixed corrrectly?

I had a similar issue to yours. Although I think yours is the V8 model so our exhaust systems are a little different. I actually sacrificed the heat shield so I could see what i was doing. This did not fix my error code though.

 

Yeah I got it fixed! So I swapped the rear 02 sensors to see if the code would switch side which it did. So for you if it's an o2 sensor it would go to p0430 now.

I put a new sensor in and all good.

 

That might work if I had two downstream sensors like I'm thinking yours has from what I've read, but I'm not a 100%. My exhaust comes from the engine and it joins into one pipe on the passenger side, There's the sensor above the cat, then there's the cat, and then there's the 02 sensor which is the one I had to do the repair on.

 

Did you clear your code and did it come back ? Or everything's okay now ? If not are you able to swap the 02 sensor front to back?

 

Cleared the codes, and returned. I did not swap them because I thought upstream, and down stream were different.

I think Denso has two different part numbers for them. I am not 100% on this.

 

This is what Denso.com shows for my truck.

 

I hope it's not your catalytic converter. Do you have exhaust leaks near the o2 sensor ? You could be getting fresh air coming in and throwing a code. Leaking manifold ? You could try one more quick fix before pulling the trigger on a new cat .

SEAFOAM

https://youtu.be/azpIa_sz9XU

Hopefully you catalytic converter is not clogged up. You can always try seafoam

 

Hell, I might just try that tomorrow. Unless someone else chimes in saying this is a No-No. This has eluded me for years. Guess this is a cheap way to see if I have leaks also like his appears to in front of the rear tire?

His engine bay needs a good pressure washing, YUCK!

 

What repair did you have done and what was the engine code?

That guy doing to seafoam didnt fix a thing with it. He didn't even know what the problem was, disconnecting the battery will clear the code temporarily. Bet that light came back the next day.

 

P0420 is the code I have been struggling for years on. I have tried replacing both upstream, and down stream sensors. I've poked around the engine bay a few times. Nothing stood out to me as obviously wrong.

 

Which sensor did you replace? You mentioned only seeing one downstream sensor. You should have 2, you have 2 cats and each has a before and after sensor.

When you replace a sensor go with Denso, these trucks don't always like Bosch or other sensors for some reason.

 

The one I quoted was downstream.

I'm pretty sure the V6 only has 2 sensors. One before the 1st cat, and one after the 2nd cat before muffler. Both sensors I am aware of are denso now. The upstream was some bastard brand I'd never even heard of when I replaced it. I'm sure it was some cheap knock off that someone had put on.


^^^ This is a Tacoma, but thats basically what my downstream looks like.

 

Check the other side. On the drivers side crawl under the truck and look around. If you have 2 cats then you'll have 4 sensors, otherwise they'd never be able to tell if the driver side cat was working.

 

@Tundra2 @04 Tundra
Thought I’d chime in. I recently replaced all my 4 of o2 sensors, Bank 1 (driver side) & Bank 2 (passenger side) and Sensor 1s (upstream/front of cats) & Sensor 2s (downstream/behind the cats). I started by replacing both upstreams and only the downstream for bank 2, per my codes. All codes cleared then I got P0420 a day later, meaning a few diff things. Could’ve been bad cat, bad bank 1 sensor 2, or what have you. So I went and got that sensor, made sure my electrical connectors were fine, tightened all my sensors some more, and put in that last sensor. Code never showed itself since.