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.
Code 23, Intake Air Temp Sensor CKT, Low Temp Indicated: Notes
IAT sensor uses a thermistor to control signal voltage to ECM. ECM applies 4-6 volts on Red/Black wire to sensor. When intake air is cold, sensor resistance is high. ECM will sense high signal voltage. As intake air temperature warms, sensor resistance decreases, and voltage drops.
Code 23 will set if voltage input at ECM indicates an air temperature below 52°F (-47°C) for at least 5 seconds.
- This test simulates Code 25. If ECM stores Code 25, ECM and its wiring are okay, and IAT sensor is faulty. If Code 23 resets, IAT sensor is okay, and wiring to ECM or ECM is faulty.
- This test determines whether there in an open in the Red/Black or Gray/Yellow wires, a short to B+ in the Red/Black wire or a faulty ECM.
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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.
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