P0112
Intake Air Temperature Circuit Low Input
Powertrain Fuel and Air Metering Air Temperature Sensing 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The engine computer detected that the intake air temperature sensor is reading colder than physically possible, like a thermometer stuck at freezing on a hot day. This tells the ECU something is wrong with the sensor circuit or its wiring.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Rich fuel mixture (black smoke from exhaust)
Poor fuel economy and sluggish acceleration
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECM monitors voltage from the Intake Air Temperature (IAT) sensor, which is a thermistor that changes resistance based on air temperature. The sensor normally reads between -40°F and 250°F; a low input fault occurs when the voltage signal falls below the minimum acceptable threshold, indicating either a shorted sensor, damaged wiring, or connector issue.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
IAT Sensor Voltage 0.5V to 4.5V (representing -40°F to +250°F) Below 0.1V or stuck at minimum value
Air Temperature Reading -40°F to +250°F Below -50°F or implausibly cold
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
IAT sensor connector
Inspect and reseat the connector at the intake air temperature sensor for corrosion or loose pins.
2
Wiring harness (IAT circuit)
Check the sensor wiring for breaks, shorts, or damage between the sensor and ECM.
3
Intake Air Temperature sensor
Replace the sensor if voltage readings are erratic or stuck low after connector and wiring checks.