Stupid Oxygen Sensor Question - Replace in pairs?

[JeffKeryk]

2001 Tundra 4.7 with 212K threw a P0161 trouble code. Replaced Bank 2 Down stream O2 sensor. Easy peasey. Amazon Denso return, pretty cheap!
Some say replace them in pairs. Your thoughts?

Told ya it was a stupid question! Thanks in advance.
I am keeping this truck forever; new ones are stupid expensive plus I would cry if it got scratched.
Here's a real truck; no extra charge.

 

[Warstud]

If it aint broke .....dont fix it . I might if they are cheap .

 

[edyvw]

Always all of them.
Are you sure there are 2 or 4?

Edit: I see you mentioned Bank 2. I would replace both Bank 1 and 2.

 

[SC Maintenance]

I don't - there is no time savings to doing them in pairs. As long as the fuel trim on the other side looked ok. In fact even if I were going to replace both, I would do one at a time. When I have an actual problem I only replace one part at a time until I know its fixed. Work with a single variable.

Now if the long term fuel trims on the other side looked a little off as well, I might.

 

[spasm3]

Down stream don't seem to fail as often , so u would not do both, unless its cheap to do so. Upstreams, I always replace both if its a pair.

 

[JeffKeryk]

I replaced the 2 upstreams last year. So 3 outta 4 are done.
Maybe I should hurry before someone steals the cats?

 

[Jethro_Bob]

Upstream pairs, downstream if it ain't broke don't fix it.

 

[GMFan]

Just got a P0139 code on my car the other night for the downstream O2 sensor. It’s original with 182K miles. I have an OEM O2 sensor on order. The upstream O2 sensor threw a code and was replaced at 150K miles.

The sensors are around $70-90 each. If it ain’t broke, don’t fix it. When it goes it will throw a CEL code. However I do recommend going for OEM sensors.

 

[justalubetech]

With more modern cars just change it when it throws a code, they have pretty specific parameters to keep the pcm happy now.

Something like my old '92 Ranger, you could have a sensor barely doing anything and it still won't throw a code.

 

[brages]

I replaced the 2 upstreams last year. So 3 outta 4 are done.
Maybe I should hurry before someone steals the cats?

In my opinions, the downstream doesn't have much (any?) effect on fuel mixture AND the failure you had was more of a random failure than a "worn out" failure. So I wouldn't do anything.

 

[dkryan]

2001 Tundra 4.7 with 212K threw a P0161 trouble code. Replaced Bank 2 Down stream O2 sensor. Easy peasey. Amazon Denso return, pretty cheap!
Some say replace them in pairs. Your thoughts?

Told ya it was a stupid question! Thanks in advance.
I am keeping this truck forever; new ones are stupid expensive plus I would cry if it got scratched.
Here's a real truck; no extra charge.
View attachment 142624

The question is valid……..not stupid.

Now, tell us about that truck!

And to keep it on topic with your original post, how many 02 sensors does it have?

 

[JeffKeryk]

The question is valid……..not stupid.

Now, tell us about that truck!

And to keep it on topic with your original post, how many 02 sensors does it have?

The 4.7L V8 engine in the 1st gen Tundra has 4 sensors; Bank 1 and 2, upstream (pre-cat) and downstream (post-cat). Toyota uses Densos. Pretty standard stuff...
I have replaced 3; the last one is the Bank 1 downstream. I will let it go for a little while and probably replace it as well.

The truck is a 1946 Dodge 3/4 ton; 1st post war truck. My older brother's friend, Dave, got it for his HS graduation in 1969 I believe. It has 300K miles of service, at least. Flat head engine, 4 speed with granny 1st gear. Dave passed away a couple of years ago; he had cancer but kept it to himself. I helped him sell his beloved Flattie about a year before he passed. He was not able to drive much and we wanted to find a good home. Some filthy rich guy bought it for his wife to go to the flower nursery in, and for parades. He sent over his mechanic driver with a flatbed trailer to pick it up. I think their west coast home was in the gold country or something.

 

[nthach]

I only change O2s if the CEL gleans to that - they do get lazy over time but even the ECU can use a lazy sensor to monitor the cats or adjust the fuel trims/calibrate the upstream AFS(Toyota does use the downstream O2s to “calibrate” the upstream sensors when it does run the cat monitor).

O2 sensor replacement was called for by the Germans, every 50K - remember the O2-SENSOR light in older Mercedes and VWs?

 

[cb450sc]

My primary oxygen sensor went in early January on my 2005 Civic. The secondary went a month later. Just saying...

 

[edyvw]

Always all! New ones will work better. O2 sensors are simple and pretty much same. Values margine might be different on different cars. On BMW’s they are very tight and BMW actually advises to change ALL at 100k regardless whether there is CEL or not. Last year I got code (not CEL) for upstream on Bank2. Replaced all 4, done with it. On Toyota there might be wider margin, but doesn’t mean it operates at optimal trim value.

 

[dumkid]

i replace the upstream ones in pairs, because they affect how the engine runs. i replaced my upstream sensors recently because one of them refused to put out more than 0.2v after a wot pull. after a few minutes of the fuel trims richening the sensor would suddenly read full rich and then work normally. kept getting fuel trim codes. replaced sensors and no more codes, and my fuel trims have dropped a few points.

 

[IndyIan]

Always all! New ones will work better. O2 sensors are simple and pretty much same. Values margine might be different on different cars. On BMW’s they are very tight and BMW actually advises to change ALL at 100k regardless whether there is CEL or not. Last year I got code (not CEL) for upstream on Bank2. Replaced all 4, done with it. On Toyota there might be wider margin, but doesn’t mean it operates at optimal trim value.

Along the lines of "If you have to ask, you can't afford it" what does 4 oxygen sensors cost for your bmw?

I had to search myself, from https://www.e90post.com/forums/showthread.php?t=1844284 from this poor guys dealer for his 328xi.

1 - Oxygen sensor replacement $1,696 for Bosch, and $2,391 for OEM BMW brand with parts and labor.

And then someone else on the board, says you can go to pelican parts and get them for $120 each, buy the socket and do it yourself.

I guess on the track when you go into open loop mode, the front O2 sensors don't do anything anyways, but I suppose its always nice to have your engine running closer to the intended A/F ratio on the street.

I only done two O2 sensors, on our 92 Sentra and then the 95 Neon. Our 03 Tracker O2 sensor and catalytic converter got with the program and passed emissions with an italian tune up, and showing up to the test with the exhaust system pinging hot.

 

[brianl703]

I guess on the track when you go into open loop mode, the front O2 sensors don't do anything anyways, but I suppose its always nice to have your engine running closer to the intended A/F ratio on the street.

LTFT and STFT don't go to 0 when in open loop in any vehicle I've ever looked at. So even in open loop it seems to be using fuel trim corrections learned in closed loop...which requires o2 sensors that work.

 

[edyvw]

Along the lines of "If you have to ask, you can't afford it" what does 4 oxygen sensors cost for your bmw?

I had to search myself, from https://www.e90post.com/forums/showthread.php?t=1844284 from this poor guys dealer for his 328xi.

And then someone else on the board, says you can go to pelican parts and get them for $120 each, buy the socket and do it yourself.

I guess on the track when you go into open loop mode, the front O2 sensors don't do anything anyways, but I suppose its always nice to have your engine running closer to the intended A/F ratio on the street.

I only done two O2 sensors, on our 92 Sentra and then the 95 Neon. Our 03 Tracker O2 sensor and catalytic converter got with the program and passed emissions with an italian tune up, and showing up to the test with the exhaust system pinging hot.

Hmmm, what is your point?
BOSCH sensors are between $70 and $96 currently. They are not anywhere more complex to replace than on other small vehicles with inline six engines. I would say, probably not anymore complex than on Toyota Sienna I had.
What track has to do about it?
On Sentra it is probably easier to replace, but then, it is Sentra.