P0112: OBD-II code P0112 means the IAT sensor is reading impossibly cold — typically a short-to-ground or a shorted internal thermistor.

Symptoms

• Check engine light is on; engine may run rich because the PCM thinks the incoming air is very cold.
• Poor cold-start fuel economy and slightly reduced power on warm days from over-enriched fuel mixtures.
• Symptoms are subtle on many engines — many drivers won't notice until they scan for codes.

Common causes

• A shorted-to-ground signal wire between the IAT sensor and the PCM.
• A failed IAT sensor with an internally shorted thermistor reading effectively zero ohms.
• Corroded pins in the connector creating a low-resistance path to ground.

What to do?

Disconnect the IAT sensor — the reading should jump to −40 °F (open circuit). If it stays low, the signal wire is shorted to ground. Measure sensor resistance and compare to spec. Replace sensor or repair wiring.