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Originally Posted by Antigenus
oxygen sensors dealer only? I was under my car yesterday and they looked fried. If im replacing the manifold to the 2to1 cat I might as well replace the o2 sensors also huh? Let me know how much the sensors are if you know off the top of your head.
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Little know fact: O2 sensors can sometimes be repaired. 1st step is to remove them and bench test them. You must use a high impedance DC voltmeter. Clamp the sensor in a vice, or use a pliers or vice-grip to hold it. Clamp your negative voltmeter lead to the ground lead wire of the sensor, and the positive to the output lead wire. Use a propane torch set to high and the inner blue flame tip to heat the fluted or perforated area of the sensor. You should see a DC voltage of at least 0.6 within 20 seconds. If not, most likely cause is open circuit internally or oil fouling. If OK so far, remove from flame. You should see a drop to under 0.1 volt within 4 seconds. If not it is likely silicone fouled. If still OK, heat for two full minutes and watch for drops in voltage. Sometimes, the internal connections will open up under heat. This is the same as a loose wire and is a failure. If the sensor is OK at this point, and will switch from high to low quickly as you move the flame, the sensor is good. Bear in mind that good or bad is relative. ANY O2 sensor that will generate 0.9 volts or more when heated, show 0.1 volts or less within one second of flame removal, AND pass the two minute heat test is good regardless of age.
If the sensor tests bad, switch to a MAPP gas or Oxy/Acetylene torch. Heat the perforated area and then remove the heat and blast the sensor with compressed air. Retest, repeat cleaning if necessary, retest. If it does not test normal at this point, replace it. Most sensors that are fouled can be cleaned successfully.
When replacing a sensor, don't miss the opportunity to use the test above on the replacement. This will calibrate your evaluation skills and save you money in the future. There is almost always *no* benefit in replacing an oxygen sensor that will pass the test in the first paragraph.
Doug