Re: At my wits end.
 

It has nothing to do with the solder material. It has to do with the fact that the O2 sensor uses reference oxygen derived from the path of the wire. Soldering the wire will inhibit the path an can/will give false or erroneous readings. Some O2 sensors use the body of the sensor itself to obtain the oxygen reference(denoted by holes/or slots in the body)

Re: At my wits end.
 

I've never heard that before. I always thought the O2 sensor generated voltage based on the amount of mixture going over the tip. More oxygen = less voltage, more gas = more voltage. I thought the computer supplied the base voltage, and a good solder joint shouldn't affect that at all. Or am I way off base here?

Re: At my wits end.
 

Yes, way off base. The O2 sensor operation is based on the Nernst Principle. A simplified breakdown is that the disparities in oxygen levels between the reference air and exhaust stream generate their own voltage signals when they come into contact with the sensors heated ceramic center. The voltage serves as the index of how much the oxygen varies on the two sides of the sensor. The amount of residual oxygen in the exhaust stream fluctuates sharply with changes in the engines air/fuel ratio.

*This info excerpted from Bosch training*

Re: At my wits end.
 

Ok, I see. But how does soldering wires above the sensor come into play? If one side of the sensor is in the exhaust stream, the other end of the sensor is in "clean" air, the electrodes on each side provide the electrical output, and that voltage is sent to the computer, I'm not seeing how soldering the wires outside of the sensor would interrupt or impact the sensor operation. Is it the heat generated by the soldering iron going to screw up the electrodes, and if that's the case wouldn't a heat sink prevent that damage from happening?

I appreciate the schooling on how the O2 sensor works, DCFiver.

Re: At my wits end.
 

The reference air signal comes from the wire harness. The air travels the length of the wire and into the o2 sensor. If you were to slit an O2 in half you would see the wire travel all the way to the center element. I suppose you could solder the connection and then poke pin holes into the wire sheath. Of course then you expose the wires to the elements and corrosion will soon develop.


Lets make this easier, you will not find one "universal" O2 sensor with instructions to solder an O2. They specifically tell you to crimp and splice the wires. It would seem to be wisest to utilize the parts manufacturers instructions would it not???

Re: At my wits end.
 

I agree - if the instructions are to crimp it, then that's what should be done.