Introduction
The P0113 diagnostic trouble code indicates that the powertrain control module (PCM) has detected a high voltage signal from the Intake Air Temperature (IAT) sensor. The IAT sensor measures the temperature of the air entering the engine, allowing the computer to adjust fuel injection timing based on air density. A “high input” signal means the resistance in the sensor circuit is too high, often signaling an open circuit or a disconnected sensor.
Common Symptoms
- Check Engine Light illuminated on the instrument cluster.
- Engine hesitation or sluggish acceleration during cold starts.
- Decreased fuel economy and rough running until the engine warms up.
Primary Causes
- Disconnected Sensor Harness: The electrical plug to the IAT sensor has come loose or fallen off.
- Faulty IAT Sensor: Internal sensor failure causing infinite resistance.
- Damaged Wiring: Frayed, broken, or corroded wires in the IAT sensor circuit.
- PCM Failure: An internal fault in the engine computer (rare).
Step-by-Step Diagnosis & Fixes
- Inspect the Sensor Connection: Locate the IAT sensor on the air intake duct or mass air flow housing and verify the plug is securely locked in place.
- Check Wiring Harness: Trace the wires from the sensor to the main harness, looking for breaks or corrosion.
- Test Sensor Resistance: Use a multimeter to measure the resistance across the IAT sensor terminals. Compare readings against ambient temperature specifications.
- Replace the IAT Sensor: If wiring is intact but resistance remains out of spec (or open), replace the IAT sensor.