The 2020 Jeep Grand Cherokee's P0112 code indicates the IAT sensor circuit voltage is lower than expected. This causes the ECU to interpret the air as extremely cold, resulting in rich running conditions as it adds fuel for dense air that doesn't actually exist.
What P0112 Indicates
P0112 means the IAT circuit voltage is below the minimum threshold. The IAT sensor is a thermistor—low voltage indicates high resistance, which corresponds to very cold temperatures. If voltage is abnormally low, the ECU thinks air is extremely cold (possibly -40°F or lower), which is unrealistic in most conditions.
Grand Cherokee Engine Options
The 2020 Grand Cherokee offers multiple engines including the 3.6L Pentastar V6, 5.7L Hemi V8, and 6.4L Hemi V8. All use IAT sensors for fuel calculations. The V8 engines are particularly affected by incorrect IAT readings due to their higher fuel requirements.
Common Causes of Low IAT Signal
An open circuit in the IAT sensor causes high resistance readings (low voltage). If the sensor, wiring, or connector has a break, the circuit reads maximum resistance, interpreted as extreme cold.
A failed sensor with open thermistor element outputs low voltage regardless of actual temperature. Internal element failure causes this condition.
Corroded or damaged connector terminals can create high resistance in the circuit, causing low voltage readings. Moisture intrusion is common in the engine bay environment.
Diagnostic Approach
Check IAT readings with the engine cold—they should roughly match ambient temperature. If showing extreme cold (-40°F or similar), the circuit is likely open. Inspect the connector for corrosion, damage, or poor contact. Test sensor resistance with a multimeter—at room temperature, expect approximately 2,000-3,000 ohms. Infinite resistance indicates an open sensor.