O2 sensor replacement

Joined
Nov 9, 2008
Messages
23,725
Location
NH
My Tundra tossed a P0031 code yesterday; this appears to be upstream drivers side. Should I be doing both upstream sensors? [It's a V8 and it has 4 O2 sensors, two on each side, with each side having a separate catalyst.] I'm guessing downstream can be left alone until they toss a code.

I was able to break loose both upstreams but the passenger side looks to be "fun" in that it's in an awful spot. I tried to break loose one downstream but I think it's going to fight me.

Not sure why Toyotapartsdeal doesn't call them upstream/downstream, guessing "air fuel ratio" means upstream while "oxygen" is downstream. That seems to match Rock's Denso's cross, nice of Denso to list the Toyota p/n. Little confused why they wouldn't use the same p/n for left and right side though, must be a wiring harness length thing.

toyotapartsdeal_tundra_o2.PNG


rock_tundra_o2.PNG
 
Air fuel sensor is just another name for oxygen sensor. The upstream sensors do the work. I'd just change those. The downstream ones are probably still good and they can be a beast to remove. I'd get the Denso sensors. Price them on Amazon, too.
 
When you reinstall make absolutely sure they have copper anti seize on them or you will never get them back out if something happens you have too. I’ve broken off a few and had to extract them before and it sucks. Especially since you are up in salt country too.
 
I bought some of the copper anti-seize a while ago, although the last pair of Denso's came with it in little packets.

Starting to wonder about backing out all the ones I haven't touched yet and adding some. Maybe this summer.
 
I bought some of the copper anti-seize a while ago, although the last pair of Denso's came with it in little packets.

Starting to wonder about backing out all the ones I haven't touched yet and adding some. Maybe this summer.
I definitely would. But then again it maybe best just to leave them be too.
 
I definitely would. But then again it maybe best just to leave them be too.
If they break loose without too much effort, then I'd like to remove them. Before I have to. If they're stuck though then I'll leave 'em alone, pay a shop to replace if the time ever comes. There's value in busting loose things that will need to be--like rotors, get them off early, slap some anti-seize back there, that way I know they will come apart in 5 years or whatever when I need new rotors.
 
If they break loose without too much effort, then I'd like to remove them. Before I have to. If they're stuck though then I'll leave 'em alone, pay a shop to replace if the time ever comes. There's value in busting loose things that will need to be--like rotors, get them off early, slap some anti-seize back there, that way I know they will come apart in 5 years or whatever when I need new rotors.
That’s true. 🙂. I was on my other forum the other day and someone had to extract one so they just took it to a shop. That shop used the anti seize and told them hopefully they won’t have anymore issues.
 
I'd do what caused the code and leave the old but good one in place.
He didn't mention the mileage but if it's over 100k, they're probably overdue to be changed. Even if they don't throw a code, the older they get, the lazier they get so you get slightly better gas mileage by replacing them even if there's no code. I replaced mine on my Mercedes, they had them on clearance for $50. Those Toyota ones are 3x the cost of Mercedes ones! That error code was a heater circuit failure. Either the oxygen sensor was bad or there was a wiring fault. Either way with the age of the sensor, you're not saving any money by just fixing it, you're going to have to replace it soon anyways.
 
I'm certain all threaded Denso exhaust sensors come with packets of anti-seize. What's funny though, is they give enough to cover 5+ sensors in every single box. I wonder how many people figured they must use the whole thing and glob it all on the sensor threads? LOL
 
I'm certain all threaded Denso exhaust sensors come with packets of anti-seize. What's funny though, is they give enough to cover 5+ sensors in every single box. I wonder how many people figured they must use the whole thing and glob it all on the sensor threads? LOL
The last O2 sensor I bought already had the threads covered in anti-seize, guess they didn't trust the customer to put the packet on.
 
btw, afr sensors are different from O2 sensors, look it up 😘
yeah, my 02 camry as well as all my prii take wide band 02 sensors or AFRs.

Thought the camry needed one "just because" and got a generic 02 sensor to splice in-- it immediately hated it.

The prii do some lean burn tricks, 17:1 AFR at cruise at 50 mph. The toyota computers seem to want to know more than just the traditional rich/lean flip-flop.
 
The last O2 sensor I bought already had the threads covered in anti-seize, guess they didn't trust the customer to put the packet on.
Sounds smart, IMO, except if the grease made its way into the sensor holes while bouncing around in shipping. I wonder if that would ruin the sensor if anti-seize got in there?
 
Sounds smart, IMO, except if the grease made its way into the sensor holes while bouncing around in shipping. I wonder if that would ruin the sensor if anti-seize got in there?
It came in a bag and none of it got on any other part of the sensor aside from the threads.
 
I recall reading somewhere that the OEM could use a wideband upstream and narrowband downstream, that the narrowband could be used to calibrate the wideband (sweep between rich & lean and find where narrowband is centered--then read wideband). In closed loop it should be darn close to correct coming out of the cat, so no real need for wideband after the cat. The cat should be ironing out the emissions. But pre-cat wideband can be more useful to the ECU. Never heard of them as air/fuel sensor though, just always "O2" or more recently upstream/downstream.

My truck is rapidly becoming a beater, but it's only at 160k. Original sensors. Probably keep for another year or two. But who knows.

$229 from Rock is $1 more than Amazon but should get here sooner, would like to install during our warm spell this week.
 
Back
Top