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.
Intake Air Temperature (IAT) Sensor (Some Engines)
IAT sensor is a thermistor (temperature sensitive resistor) mounted in the intake manifold. Low intake air temperature produces high internal sensor resistance, while high temperature causes low internal sensor resistance. The PCM supplies and monitors a 5-volt signal to sensor through a pull-down resistor in PCM.
IAT sensor, also known as an manifold air temperature sensor, allows PCM to determine intake air temperature. PCM uses signal to delay EGR until intake air temperature reaches about 40°F (5°C). If intake air temperature becomes excessively high, PCM compensates by slightly retarding ignition timing. After a vehicle has sat overnight, IAT and CTS signals (resistance and temperature) should be close to same reading. Failure in IAT sensor circuit should set a related trouble code.
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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.