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 Sensor: Inspection: Inspection
- INSPECT AIR FUEL RATIO SENSOR (w/ Secondary Air Injection System)
- Measure the resistance according to the value(s) in the table below.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
TEXT IN ILLUSTRATION*a Component without harness connected
(Air Fuel Ratio Sensor)*b for Bank 1 *c for Bank 2 Standard Resistance (for Bank 1)
Tester Connection Condition Specified Condition 1 (HA1A) - 2 (+B) 20°C (68°F) 1.6 to 3.2 Ω 1 (HA1A) - 4 (A1A-) Always 10 kΩ or higher Standard Resistance (for Bank 2)
Tester Connection Condition Specified Condition 1 (HA2A) - 2 (+B) 20°C (68°F) 1.6 to 3.2 Ω 1 (HA2A) - 4 (A2A-) Always 10 kΩ or higher If the result is not as specified, replace the air fuel ratio sensor.
- Measure the resistance according to the value(s) in the table below.
- INSPECT AIR FUEL RATIO SENSOR (w/o Secondary Air Injection System)
- Measure the resistance according to the value(s) in the table below.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
TEXT IN ILLUSTRATION*a Component without harness connected:
(Air Fuel Ratio Sensor)*b for Bank 1: *c for Bank 2: Standard Resistance (for Bank 1)
Tester Connection Condition Specified Condition 1 (HA1A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 Ω 1 (HA1A) - 4 (A1A-) Always 10 kΩ or higher Standard Resistance (for Bank 2)
Tester Connection Condition Specified Condition 1 (HA2A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 Ω 1 (HA2A) - 4 (A2A-) Always 10 kΩ or higher If the result is not as specified, replace the air fuel ratio sensor.
- Measure the resistance according to the value(s) in the table below.
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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.