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Home >> Toyota >> 1992 >> MR2 2.0 S >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Engine Sensors & Switches >> Engine Controls - System & Component Testing >> Sub-Oxygen Sensor (Non-Turbo)
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Sub-Oxygen Sensor (Non-Turbo)

  1. Warm engine to normal operating temperature. Check ECU for stored code(s). See RETRIEVING CODES in TESTS W/CODES article in the ENGINE PERFORMANCE Section. If sub-oxygen sensor or circuit fails, a Code 27 will set in ECU memory. Clear codes if present. See CLEARING CODES in TESTS W/CODES article in the ENGINE PERFORMANCE Section.
  2. Drive vehicle between 50 and 62 MPH for at least 5 minutes in 4th or 5th gear (M/T) or Drive (A/T).
    CAUTION: DO NOT drive vehicle at speeds exceeding 62 MPH or code will be canceled.
  3. Fully depress accelerator pedal for at least 2 seconds.
  4. Stop engine and turn ignition off. Repeat steps and note if Code 27 exists again. If Code 27 exists again, check sub-oxygen sensor circuit for continuity, shorts or grounds. Replace sub-oxygen sensor if circuit is okay.
NOTE: For oxygen sensor heater or sub-oxygen sensor heater application, see OXYGEN SENSOR APPLICATION table.
NOTE: A Code 21 is also an indicator of a problem in oxygen sensor circuit. Code 21 will set if sensor heater circuit opens or shorts to ground on HT wire from sensor to Electronic Control Unit (ECU).
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