Heated Oxygen Sensors for OBD applications

[DrNoKnow]

I'm interested in operating parameters for O2 sensors, AS THEY APPLY, in OBD2 & OBD3 automobiles. Specifically, upstream & downstream design differences.

With respect to the diagnostic capacity & capability of differentiating between sensor failure, sensor degradation, or "are they just stupid", techs need some good reference material.

I know you can't help the fleet of techs or part wingers who just don't "get it". Some of these specifics are not widely known or understood very well by a majority of automotive repair technicians.

Almost 30 years of automotive application of these devices, should warrant more education of both consumers, engineers, & technicians in the diagnosing/repairing business.

 

[reidh]

Is your question what is the difference between an upstream and downstream O2 sensor?

If that is your question, the upstream sensor monitors the combustion products of the engine, while the downstream sensors monitor the effectiveness of the catalytic converter.

There are some tests you can do to check your sensor: Heating the sensor and checking the output wire of at least half a volt. You can watch the sensor change voltage as the flame is moved towards and away the sensor. I'm not sure of any other tests you can do.

They do degrade, but I do not know how to quantify this.

Its probably not worth it for a automotive technician to troubleshoot these in a shop. For the cost of troubleshooting, repair, and possible replacement, it would likely be cheaper just to replace it initially.

If you have more specific questions, please let us know.

Reidh

 

[nemmi69]

As reidh said its probably not worth checking. You need an oscilloscope and ways to check the system is currently running closed loop and to also maintain a constant speed and load ( I used to do OBD vehicle set up testing). They do degrade with age and this can be seen as a widening of their swing (lean to rich)and a bias towards rich or lean. Also note the cats deteriorate with age to (which hopefully the down line sensor catches.