Heated Oxygen Sensor (Ho2S)

HO2S is located in exhaust pipe, upstream of the catalytic converter. Faults in sensor or circuit should set a service code. See QUICK TEST in appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE section below. If no service code has been set, see CIRCUIT TEST H in appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE section for additional sensor specifications and circuit testing procedures. Ensure following conditions do not exist:

• TESTS W/CODES (for B4000)
• TESTS W/CODES (for Navajo)
• Moisture inside sensor/harness connector.
• HO2S coated with contaminants.
• Sensor circuit open or shorted to ground.