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Hello everyone, so I guess this is an "in general" type question. But what does everyone consider a lazy oxygen sensor to be? Narrow band, nothing fancy. At idle more on this truck, I can get them to swing when out driving, and yes I'll admit this thing has a small vacuum leak, but I do notice the 02s just seem to react slow altogether. It's a 2001, and I doubt they've ever been changed. But I'm just seeing some long hang times, rich and lean from both, not always at the same time. I've looked at fuel trims and all that good stuff, I've had 02s stuck rich or lean, but I'm wondering more about how lazy can an 02 get without being stuck one way or another. I understand too that the heater circuits come into play for this question, let's say they're ok. These are just old sensors and tend to hang out wherever they feel like chillin'. That's why this is an in general question. That's all, thanks guys
First of all are you looking at the upstream sensors on a V engine these are B1S1 and B2S1 At idle even a small vacuum leak as a big effect on O2 control
Normally under closed loop on a warm engine expect the upstream signals to switch at around once per second.
If the heater circuit or heater elements aren't working then normally with the vehicle stationary raising and holding the RPM at around 2,500 for a ten or twenty seconds should raise the temperature sensor enough to getting it hot enough to start switching for a short while RPM returns to idle.
Yeah I understand all that, I'm just curious as to what others consider to be a lazy 02, that's all. Granted yes narrow band 02s are supposed to swing fast, so your definition of a lazy 02 is just slower swing times? No slower swings at idle versus let's say 2500rpm. Or hanging rich/lean and slowly getting back into a slower swing. Maybe I should have worded this differently, I mean having to work on every make and model, fuel trims and strategies can be so different from make to make, even the older vehicles have pretty interesting fuel mapping strategies. I'll just keep an eye on the 1 second swing for reference.
The criteria for "slow" sensors is defined in the respective generic OBD2 code setting conditions. In general it refers to the time required for a rich to lean or vice versa transition. Just look up the specific code. The attached document describes on page one the P0133 code setting using a Toyota Corolla 2004 as example.
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Last edit: 3 years 10 months ago by juergen.scholl.
That's a good idea, I didn't really think to look up code setting criteria, I don't have any codes, their waveforms just look slow to me. Thanks for the idea though.
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