Quote:
Originally Posted by lendaddy
Then test the O2 sensor itself- find the ground wire (it's the one that has continuity between itself and the body of the sensor). Test for DC voltage between that wire and the remaining wire of the 4 while holding a torch over the sensor end. After a few seconds you'll start to see a slow climb to .1 volts or so, remove the flame and it will head back down to zero. If it does this the sensor is good.
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My memory and tech knowledge is a bit fuzzy on this, but...
I think the O2 sensor creates a 0-1 volt signal using heat to active the differential potential in the layers of platinum. It uses the comparison of external oxygen vs. that inside the tailpipe. Even though the sensor inside the pipe may generate some sort of a voltage signal, that signal may or may not be calibrated correctly to the level of ambient oxygen.
The O2 sensor was made specifically for the catalytic converter which needs brief cycles of lean mixture to keep it heated and clean.
In post-1994-5 OBD2 vehicles, the long-term fuel curve usually recognizes and compensates for a "weaker" O2 sensor unless it's completely out of whack. If the signals returned are outside the computer's preceived ability to compensate, it sets the code and dash-light.
It could be a toss-up between the extra cost of gas over x-years vs. the cost of the new sensor.
Certainly, a rusted sensor with opaque oil in the engine is not even worth the trouble of looking at.
That being said.....thanks for memory reminder. Junkyards are definitly a great resource for all those those "little things" and a lost art.