Technical Definition:

O2 Heater Circuit (Bank 1, Sensor 3)

Technical Description:

O2 (Oxygen) sensors contain a heating element that allows the sensor to reach operating temperature quickly. This lowers emissions since it allows the engine to reach closed loop faster and also allows the engine to stay in closed loop at idle.

Possible Causes:

• Bad o2 sensor heater circuit
• Bad o2 sensor
• Wiring harness problems

Possible Symptoms:

• MIL (Malfunction Indicator Lamp) illumination
• Poor/ rough idle

O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 3

Possible Solutions:

OBD-II Trouble Code Type:

Diagnostic Step:

Tech Notes:

– Faulty Heated Oxygen Sensor Bank 1 Sensor 3
– Heated Oxygen Sensor Bank 1 Sensor 3 harness is open or shorted
– Heated Oxygen Sensor Bank 1 Sensor 3 circuit poor electrical connection

Specific Makes:

– High Fuel Consumption
– Excessive Smoke from Exhaust