Staff Answer
May 29, 2026 - 01:02 PM
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The P0113 code triggers when the Engine Control Module (ECM) receives an exceptionally high voltage signal from the Intake Air Temperature (IAT) sensor. Because the sensor’s resistance increases as air temperature drops, a "High Input" signal tells the computer that the incoming air is impossibly cold (often reading $-40^{\circ}\text{C}$ or $-40^{\circ}\text{F}$ on a scanner). To protect the engine, the ECM defaults to a rich fuel mixture, which causes poor fuel economy and difficult warm starts.
Common causes for the P0113 high input signal include:
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Internal Sensor Open Circuit: The most frequent cause is a failed IAT sensor where the internal thermistor has broken. This creates an "open" circuit with infinite resistance, which the ECM interprets as maximum voltage (high input).
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Broken or Cut Wiring: Since the IAT sensor is often located on the air intake tube, the wiring can become brittle over time. A broken signal wire or a wire that has pulled out of the connector will mimic a failed sensor by creating an open circuit.
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Corroded Connector: Moisture or road salt can enter the sensor plug, causing corrosion on the metal pins. This corrosion increases electrical resistance or breaks the connection entirely, triggering the high voltage error.
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Loose Electrical Connection: If the locking tab on the sensor connector is broken, engine vibration can cause the plug to back out slightly, leading to an intermittent or constant high input signal.
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Poor Ground Circuit: If the ground wire leading from the sensor back to the ECM is damaged or disconnected, the circuit cannot complete, causing the signal voltage to spike to its maximum reference level.
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