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Home >> Toyota >> 1994 >> Pickup Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Engine Sensors & Switches >> Sub-Oxygen Sensor
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Sub-Oxygen Sensor

NOTE: Sub-oxygen sensor may be used only on California applications on some models. See OXYGEN SENSOR APPLICATION  table.
  1. Warm engine to normal operating temperature. Check Engine Control Module (ECM) for stored diagnostic trouble code(s). See RETRIEVING TROUBLE CODES in articles listed below:
    • TESTS W/CODES - 4-CYL
    • TESTS W/CODES - V6

      If sub-oxygen sensor or circuit fails, a diagnostic trouble Code 27 will set in Engine Control Module (ECM) memory. Clear diagnostic trouble code if present. See CLEARING TROUBLE CODES in articles listed below:

  2. Drive vehicle at speeds less than 50 MPH for at least 5 minutes in 4th or 5th gear (M/T) or Drive (A/T). On all models, fully depress accelerator pedal for at least 2 seconds.
  3. Stop engine and turn ignition off. Repeat steps and note if diagnostic trouble Code 27 exists again. If trouble Code 27 exists again, check sub-oxygen sensor circuit for continuity, shorts or grounds. Replace sub-oxygen sensor if circuit is okay.
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