How exactly do O2 sensors work? Can I "spoof" the value?

[Delta1Seven]

So, I have a 2022 and not looking to clone my ECU yet. However, I do want to go catless without a CEL.

It got me thinking on how O2 sensors work. To my understanding, the output voltage of the sensor dictates the value the car will read from the sensor. Why can't I just put a potentiometer, resistors, etc in line and force the output voltage of the sensor to be a value that the car thinks is acceptable? heck, if I find a good (and repeatable) way to do this I know some of you guys on here will also want to DIY this as well.

I'm a little rusty at the moment but I used to do a lot of circuit board manufacturing. I enjoy tinkering with things and for some reason I really want to figure this out, as I know those O2 spacers really don't work long term on our cars.

Can anyone explain how exactly or O2 sensors work? And if this is even plausible assuming I learn more about them?

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[zrk]

You’ll need to compute the diff between the first O2 and the expected result from the second. But you’re not far off. Grab your oscilloscope and a sensor and get to work.

 

[Delta1Seven]

You’ll need to compute the diff between the first O2 and the expected result from the second. But you’re not far off. Grab your oscilloscope and a sensor and get to work.

I know electronics but I don't know O2 sensors and how they talk to the car.

So from what you are telling me, it takes the first O2 sensors and determines a value that the second O2 sensor should read, based on the first sensors reading?

 

[zrk]

I know electronics but I don't know O2 sensors and how they talk to the car.

So from what you are telling me, it takes the first O2 sensors and determines a value that the second O2 sensor should read, based on the first sensors reading?

First O2 sensor is going to read some value, second O2 is going to read some different value. The diff in these values needs to be within some tolerance (no idea what this tolerance is.. it’ll take some investigating). Basically to determine if the Cat is “working.”

If you can trick the second O2 to report a value (or rather, report that value yourself as a voltage) over the sensor harness, as a function of the value that is being reported by the first O2, you should be in business.

 

[Delta1Seven]

First O2 sensor is going to read some value, second O2 is going to read some different value. The diff in these values needs to be within some tolerance (no idea what this tolerance is.. it’ll take some investigating). Basically to determine if the Cat is “working.”

If you can trick the second O2 to report a value (or rather, report that value yourself as a voltage) over the sensor harness, as a function of the value that is being reported by the first O2, you should be in business.

Thanks for the info.

I'm curious as to what happens to the readings when you increase throttle (WOT for example). I ASSUME the first O2 sensor reading will change, which will than require the 2nd sensor need to report a correct corresponding value. This will be the most challenging part.

If the readings can be constant, I can wire this up tomorrow lol. But I assume that is not the case lol

 

[zrk]

Thanks for the info.

I'm curious as to what happens to the readings when you increase throttle (WOT for example). I ASSUME the first O2 sensor reading will change, which will than require the 2nd sensor need to report a correct corresponding value. This will be the most challenging part.

If the readings can be constant, I can wire this up tomorrow lol. But I assume that is not the case lol

Readings are very much not constant. You’ll have to take the output of the first O2 into your circuit to calculate the value for the second.

 

[MisterSkiz]

 

[FLtrackdays]

Is that similar to these @MisterSkiz ?

O2 Simulator Mini Cat Cel Fix stainless steel Rear O2 sensor simulator. (bigdaddiesgarage.com)

I swear I don't work for these mini cats ? but the thing is still working for me with my catless dp. I've seen other post where it doesn't work for some.

 

[MisterSkiz]

Is that similar to these @MisterSkiz ?

O2 Simulator Mini Cat Cel Fix stainless steel Rear O2 sensor simulator. (bigdaddiesgarage.com)

I swear I don't work for these mini cats ? but the thing is still working for me with my catless dp. I've seen other post where it doesn't work for some.

Nope, this video above is basically an 02 Sensor Massager that modifies/smooths the signal coming out - I have no clue if it will work for our cars.

Its good to know that your simualtor is working - I have seen many folks who say on here they did not work for them I think in the next coming years you are going to find folks on here freaking out about not being albe to pass emmissions.

 

[FLtrackdays]

Nope, this video above is basically an 02 Sensor Massager that modifies/smooths the signal coming out - I have no clue if it will work for our cars.

Its good to know that your simualtor is working - I have seen many folks who say on here they did not work for them I think in the next coming years you are going to find folks on here freaking out about not being albe to pass emmissions.

I'm lucky that we don't get a finger up our tailpipe here unless we ask for it ? ?

 

[syyc]

Is that similar to these @MisterSkiz ?

O2 Simulator Mini Cat Cel Fix stainless steel Rear O2 sensor simulator. (bigdaddiesgarage.com)

I swear I don't work for these mini cats ? but the thing is still working for me with my catless dp. I've seen other post where it doesn't work for some.

How hard do you drive your car? I had one of these from a different company and it only lasted ~2 months before a CEL. I assume it melted through the 'mini-cat' as it's what I read from other's diagnostics.

 

[FLtrackdays]

How hard do you drive your car? I had one of these from a different company and it only lasted ~2 months before a CEL. I assume it melted through the 'mini-cat' as it's what I read from other's diagnostics.

Good question. I‘ve only driven in town so far. No lights and I absolutely love the car! So if/when any CEL comes on, there’s no going back for me (I‘m digging the catless sound and rawness of the engine that much). I have done many full throttle pulls/logs for Jessie for my JB4 custom tune. And still nothing yet…. However I’ve got a track weekend coming up in 7 days. Y’all got me wondering if it’s going to last the brutality of this jungle humidity & high 80-90s degrees down here in Florida…. We’ll see ?‍

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