O2 sensors......proactive or reactive

hello TW Community,
I have 2010 DCSM, 218K

working my way down a list of things to replace, flush, repair and next on my list I’m looking at the “upstream” o2 sensors that look like crap, grungy and rusted....obviously OEM original.

Do I wait for them to fail and give me engine check light and code?
How hard to take off?......looks from videos , I need special tool....

all kinds of price ranges for parts....

As always, thanks in advance

 

Some people claim they can drift over time causing slightly worse MPG. Not sure I agree with that logic. Anyhow, if you're going to be removing them to replace them, no special tools are required just cut the harness off and use a regular socket. I would let them run to failure, and I personally consider them to be one of those "life of the engine" type of parts.

 

Reactive.

The ECU is always monitoring them for accuracy and compare them to the downstream sensors to see how the voltages match.

 

My originals got almost 350k. I had the rasta code, P0420 and that turned out to be a gasket.

I say wait till they throw a code. They're not cheap.

 

I personally don’t like messing with emissions components until I have too.
If there isn’t a problem, I don’t take the chance of creating one.

Like @whatstcp said, Toyota’s can be “temperamental” with AF and O2 sensors.
Might as well use the ones that are working fine now and deal with what “might” be a problem later.

 

When I got a check engine light / trac control light for em I went to replace them

But before I did, I switched the fuse for em with my fog fuse and the next day my lights went away. When I returned them to my stealership they said “no one ever buys these” because they almost never go out.

I say reactive.

 

There is a o2 sensor socket, mine is 7/8”.
There’s other sized sensor sockets but the 7/8 fit every one I did so far.
They can be a bear to get out, even if you soaked it with penetrant. On a customer vehicle I spray it cold, run the engine to heat it up. Go get the part, then it’ll come out. On my car I sprayed it, let it sit overnight, drove it, sprayed it cold overnight again. Overkill but I did that for a week, came out easy. Just make sure you’re on it good before twisting. Strip it, your screwed. I had to use a pipe wrench on one someone slipped on.