P0112: Intake Air Temperature (IAT) Sensor 1 Circuit Low

Common causes

• A failed (internally shorted) IAT sensor; on many cars it's built into the MAF sensor
• A signal wire shorted to ground, for example a pinched or chafed harness
• Water or corrosion inside the connector

Code meanings can vary slightly by manufacturer. Use these as a starting point and confirm with your vehicle's service information or a mechanic before replacing parts.

Symptoms

• Check engine light
• Sometimes hard starting when cold or slightly rough running
• Often no noticeable symptoms

Is it safe to drive?

Generally safe to drive with a steady light, but fix it so the engine computer gets accurate data.

How to check it with a scanner

1. Plug an OBD2 scanner into the port under the dashboard and read all stored codes and the freeze-frame data (the conditions when the code set).
2. After the car has sat overnight, the IAT reading in live data should be close to the outside temperature and to the coolant temperature. A reading at or near the scanner's maximum points to a short.
3. Unplug the sensor with the key on: if the reading jumps to around -40 degrees, the wiring is fine and the sensor is likely shorted. If it stays high, look for a wire shorted to ground.
4. With the key off, inspect the harness near the air box and intake for pinched or rubbed-through wires, and check the connector for water or corrosion.
5. After a repair, clear the code and drive normally for a few days to confirm it doesn't come back.

A basic code reader shows the code; scanners with live data let you watch sensor readings, which is what you need for most of the checks above. See OBD2 scanners under $100.

Questions

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