P0112 moderate

Intake Air Temperature Sensor 1 Circuit Low Input

The P0112 code means the vehicle's onboard diagnostic system has detected: Intake Air Temperature Sensor 1 Circuit Low Input. This is a moderate severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
easy
Estimated cost
$15-$150
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Common Symptoms

  • Check Engine Light on
  • Engine may run lean (ECM reads the air as hot and pulls fuel)
  • Possible hard starting when warm
  • Minor performance issues

Probable Causes (Ranked by Likelihood)

  • IAT sensor shorted internally causing low voltage Very High
  • Short to ground on signal wire High
  • Failed sensor reading stuck at extreme hot temperature Moderate

Step-by-Step Diagnostic Procedure

  1. Check IAT voltage: at room temperature should be about 2-3V. Below 0.3V indicates a short.

  2. Disconnect the IAT sensor. If voltage rises to 5V at the connector, the sensor is shorted internally.

  3. Inspect wiring for shorts to ground.

  4. Replace sensor if confirmed faulty.

Frequently Asked Questions

What temperature does a low IAT input simulate, and does it richen or lean the mixture?

A shorted (low-voltage) IAT circuit reads at the extreme HOT end of the sensor range, often around 300F. The ECU thinks the incoming air is extremely hot and pulls fuel out, leaning the mixture. (The extreme-cold, -40F condition is the opposite fault, P0113 Circuit High Input.)

Sources

This page is built from documented references. Verify against your own service info before repair work.

P0112 on Diesel, EV & Equipment

The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:

Duramax moderate Intake Air Temperature Sensor 1 Circuit Low Isuzu minor Intake Air Temp Sensor Low Kubota moderate Intake Air Temperature Sensor Circuit Low Yanmar moderate Intake Air Temperature Sensor Low

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