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.
Air Fuel Ratio (A/F) Sensor 1
FUNCTIONS WITHIN THE SYSTEM
ECM judges the state of air fuel ratio with this signal, and precisely controls air fuel ratio to match the stoichiometric ratio. Also, the sensor is equipped with heater for maintaining the activated state.
INDIVIDUAL FUNCTION WITHIN THE SYSTEM
A/F Sensor 1
The A/F sensor 1 transmits the signal of detected oxygen concentration in the exhaust gas to ECM.
A/F Sensor 1 Heater
The A/F sensor 1 heater activates A/F sensor 1.
INDIVIDUAL OPERATION
A/F Sensor 1
While O2 sensor changes output voltage by ON/OFF (rich/lean) mode within a narrow range of the stoichiometric ratio, the A/F sensor changes output voltage between 0 - 4 V for a wide range of air fuel ratio.
A/F Sensor 1 Heater
The ECM performs ON/OFF duty control of the A/F sensor 1 heater corresponding to condition to keep the temperature of A/F sensor 1 element within the specified range.
Component Location
The A/F sensor 1 is installed on the exhaust manifold.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.