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Home >> Mazda >> 1995 >> B3000 Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Computerized Engine Controls >> Heated Oxygen Sensor (Ho2S)
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Heated Oxygen Sensor (Ho2S)

NOTE: HO2S is located in exhaust pipe, upstream of the catalytic converter. Faults in sensor or circuit should set a service code. See appropriate TESTS W/CODES article.
  1. To test sensor, warm engine to operating temperature. Unplug sensor. Connect DVOM positive lead to Gray/Light Blue wire (Red/Light Green on some sensors) on HO2S. Connect DVOM negative lead to Orange wire on HO2S.
  2. Start engine and run at high and low speeds while monitoring voltage. Voltage should fluctuate between 0.2-1.0 volt. If voltage is not as specified, replace sensor.
  3. To check sensor heater, measure resistance between remaining 2 terminals. With sensor at room temperature, resistance should be 2-5 ohms. With sensor warm to hot, resistance should be 5-30 ohms. If resistance is not as specified, replace sensor.
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