P0112 on the LB7 Duramax indicates the intake air temperature (IAT) sensor is reading a low-input signal, which the ECM interprets as an abnormally high intake air temperature or an electrical fault. While the IAT is a minor sensor, it influences fueling and emissions decisions, so it is worth fixing correctly. This guide explains P0112 on the 2001-2004 LB7.
What P0112 means
P0112 is "Intake Air Temperature Sensor 1 Circuit Low Input." The IAT sensor is a thermistor whose resistance changes with temperature. A low-input reading corresponds to very low signal voltage, which usually means a short to ground in the circuit, a failed sensor, or a wiring fault rather than a genuine extreme temperature. The ECM uses IAT data to fine-tune fueling and manage air density calculations.
Common causes
- Short to ground in the IAT signal wire
- A failed IAT sensor reading out of range
- Corroded or damaged sensor connector
- Wiring chafed against the intake or engine
- Contamination on the sensor element
- Poor connection at the ECM
Symptoms
- Check engine light with P0112 stored
- Minor changes in cold-start behavior
- Slightly rough running or hesitation
- Possible small changes in fuel economy
- Rarely, driveability is unaffected other than the light
- Related intake temperature codes
How to diagnose it
Scan all codes and view the IAT reading in live data; an implausibly high temperature reading or one that does not match ambient with a cold engine indicates a fault. Inspect the sensor connector and wiring for shorts to ground, chafing, and corrosion. With the sensor unplugged, the reading should swing to the opposite extreme, which helps confirm whether the sensor or the wiring is at fault. Measure the sensor's resistance and compare to specification at a known temperature. Verify the ground and signal circuits are clean.
How to fix it
Repair any short to ground or chafed wiring and replace a damaged connector. If the sensor reads out of specification, replace the IAT sensor. Because this is a low-cost, accessible component, repairs are usually quick. After the fix, clear the code and confirm the IAT reading matches ambient temperature with a cold engine and rises appropriately as the engine warms.
FAQ
Is P0112 a serious problem?
It is usually minor in terms of driveability, but it should still be fixed so the ECM has accurate air temperature data for fueling.
Can I drive with P0112?
Generally yes, but repair it promptly so the check engine light is not masking other issues and fueling stays accurate.
How do I confirm the sensor versus wiring?
Compare the live reading to ambient, unplug the sensor to see the reading swing, and measure resistance against spec to isolate the fault.
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