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Home >> Toyota >> 1993 >> T100 Base, 4WD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Introduction >> Engine Sensors & Switches >> Sub-Oxygen Sensor
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Sub-Oxygen Sensor

  1. Warm engine to normal operating temperature. Check Engine Control Module (ECM) for stored diagnostic trouble code(s). See RETRIEVING TROUBLE CODES in TESTS W/CODES article. If sub-oxygen sensor or circuit fails, a trouble Code 27 will set in ECM memory. Clear codes if present. See CLEARING TROUBLE CODES in TESTS W/CODES article.
    CAUTION: DO NOT drive vehicle at speeds exceeding 62 MPH, or trouble code will be cancelled.
  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 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.
NOTE: Oxygen sensor heater may be used only on California applications on some models. See OXYGEN SENSOR APPLICATION table.
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