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I am getting an error code that tells of a faulty oxygen sensor on a 97 chevy 2500 van. The van runs at about half power until it warms up then it goes. I replaced plugs wires.
Did it say replace wires or Faulty O2 sensor?
Check voltage to sensor, may be 5 volts.
Others here may provide additional info.
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There are 4 wires going to the O2 sensor. You didn't tell us which engine, so I'll have to wing it on the wire color. The pink should have 12 volts to the heater inside the sensor. The black wire is the ground for the heater. The computer supplies .5 volts to the sensor on the purple wire. Depending on how much oxygen is left in the exhaust, the sensor varies the return voltage back to the computer on the tan wire. The computer sends out this small voltage just to make sure the wiring is ok to the sensor. But if the sensor is working properly, it will return a voltage reading of almost 1 volt for rich exhaust and .1 for lean. The reading switches at least 8 times per second, so you really need a scope to track the changes.
What TX is talking about with the 5 volts is that the computer provides a 5 volt reference signal to most other sensors in the car. So if you see a full 5 volts on the purple wire, that means you have a short either in the computer on in the wiring harness. If you feed 5 volts into the O2 sensor the return signal will always be higher than 1 volt and the computer will see this as a rich condition and as a wiring problem (since it's only expecting to see .5 volts at startup).
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