Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Heated Oxygen Sensor 2
FUNCTIONS WITHIN THE SYSTEM
Heated oxygen sensor 2 detects the oxygen concentration in the exhaust gases, converts it to a voltage signal, and transmits the signal to the ECM. Heated oxygen sensor 2 contains a heater for maintaining its activation.
INDIVIDUAL FUNCTION WITHIN THE SYSTEM
Heated Oxygen Sensor 2
Under normal conditions, heated oxygen sensor 2 is not used for engine control. When A/F sensor 1 is malfunctioning, the signal from heated oxygen sensor 2 is used to control the A/F ratio to the stoichiometric ratio.
Heated Oxygen Sensor 2 Heater
The heated oxygen sensor 2 heater activates heated oxygen sensor 2.
INDIVIDUAL OPERATION
Heated Oxygen Sensor 2
Heated oxygen sensor 2 is composed of a zirconia element in a test tube shape, and is exposed to the atmosphere on the inside and the exhaust gases on the outside. When there is a difference in the oxygen concentration between the inside and outside, electromotive force is generated. When the A/F ratio is leaner than the stoichiometric ratio, the voltage is approximately 0 V. When it is richer, the voltage is approximately 1 V.
Heated Oxygen Sensor 2 Heater
The ECM performs ON/OFF control of the heated oxygen sensor 2 heater corresponding to the engine speed, amount of intake air and engine coolant temperature.
| Engine speed | Heated oxygen sensor 2 heater |
|---|---|
| Above 3, 600 rpm | OFF |
Below 3, 600 rpm after the following conditions are met.
|
ON |
COMPONENT LOCATION
The heated oxygen sensor 2 is installed on the downstream side of three way catalyst (manifold).
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.