Code Definition

P1112 — IAT Sensor Circuit Intermittent Voltage Low

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Isuzu

About P1112

P1112 is a manufacturer-specific powertrain diagnostic trouble code recorded for Isuzu vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1112 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1112 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This Isuzu code indicates the Intake Air Temperature (IAT) sensor is intermittently reporting a voltage lower than the expected range. The IAT sensor is a thermistor whose resistance falls as intake air warms, and the Engine Control Module (ECM) reads the resulting voltage to adjust fuel delivery and ignition timing for air density. Because the signal voltage drops with resistance, an intermittent low voltage typically reflects a brief short to ground or a collapsing sensor resistance, which the ECM sees as an implausibly hot intake temperature. The sporadic fault can momentarily lean or riche...

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