O2 sensor vs AFR sensor

[max]

What is difference between two? Can I check air/fuel sensor same as o2 sensor with propane torch/multimeter?
I thought I had 02 sensor before cat and when removed it’s afr sensor part #89467-33020

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[Wayne]

AFR = Air Fuel Ratio, which is exactly what a named upstream “o2 sensor” is. o2 sensor is just used as a generic term to usually describe both.

The name is just different from where ever your ordering/getting that OEM one, usually differentiated from having a heating element and it’s job to correct the AFR, rather than downstream’s job of just checking to see if the catalytic converter is doing it’s by measuring it the same way, just not actually doing anything other than reporting it. In short, yes, you can use a torch to check it’s functioning, although depending on your problem or code it’s the heating element you may wish to verify.

Narrow band vs. Wide band are usually the only big differences between any of them.

[max]

What I’m wondering about is does AFR sensor have same wavelength as regular o2 sensor? I hooked up my oxygen sensor tester and it showed “lean” range without fluctuating.

[Wayne]

This I’m unsure of, however I “believe” most still use narrow band for o2, where as quite a few now use wideband for upstream. The wavelength for most on the same vehicle should still be the same, just the switching shouldn’t be much in relation.

http://www.autotap.com/techlibrary/catalytic_converters_and_o2_sensors.asp

Under normal operating conditions, the downstream O2 sensor should have little switching activity. But if the rate at which the downstream O2 sensor is switching starts to increase, it tells the OBDII system converter efficiency is dropping and there’s a potential emissions problem. If the problem may cause emissions to exceed 1.5 times the federal limit, the Malfunction Indicator Lamp (MIL) will come on and the PCM will log a diagnostic trouble code for “catalyst is below threshold efficiency” (P0420, P0421, P0422, P0430, P0431 or P0432). The bottom line here is you have a bad converter — unless the problem is something else like a bad oxygen sensor or open fuel feedback control loop.

If you have a dual trace digital storage oscilloscope (DSO) and want to confirm the diagnosis, you can hook your scope up to the upstream and downstream O2 sensors to compare their switching activity. If the downstream O2 sensor activity mirrors the upstream O2 sensor, the converter is dead and needs to be replaced.

[max]

I was wondering if I could inject some propane into intake with car idling, simulating rich condition to see if AFR sensor responds.

[Author]

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