LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 1991 >> Cressida >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Engine Sensors & Switches >> Sub-Oxygen Sensor
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Sub-Oxygen Sensor

  1. Warm engine to normal operating temperature. Check ECU for stored fault code(s). If sub-oxygen sensor or circuit fails, a Code 27 fault code will set in ECU memory. Clear codes if present. See CLEARING TROUBLE CODES in TESTS W/CODES article in the ENGINE PERFORMANCE Section.
    NOTE: DO NOT  drive vehicle more than 62 MPH or code will cancel.
  2. Drive vehicle between 50 and 61 MPH for at least 5 minutes in 4th or 5th gear (M/T) or Drive (A/T).
  3. Fully depress accelerator pedal for at least 10 seconds with engine RPM at least 3000 RPM. Stop engine and turn ignition off.
  4. Repeat previous 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.
scientia non olet · About LEMON Manuals