P0113: Intake Air Temperature (IAT) Sensor 1 Circuit High Input
The Intake Air Temperature (IAT) sensor is a Negative Temperature Coefficient (NTC) thermistor. As air temperature rises, sensor resistance drops. Trouble code P0113 is set when the ECM detects signal voltage higher than 4.85V (typically corresponding to -40°F / -40°C), which indicates an open circuit, disconnected sensor plug, or broken internal wire.
Driveability & Safety Advisory
Drivable. ECM will substitute a default assumed temperature (often 68°F / 20°C or 104°F / 40°C), resulting in slightly degraded fuel trim efficiency.
Official Manufacturer TSB Advisories
Factory Condition: IAT sensor terminal pin fretting corrosion inside MAF multi-plug causes intermittent high voltage readings.
Physical Component Location & Service Access
Integrated inside the Mass Air Flow (MAF) sensor body (5-pin or 6-pin connector) or mounted separately in the air intake duct bellows.
Electrical Specifications & Live PID Benchmarks
Scan Tool Live Data Targets
Digital Multimeter (DMM) Specs
Documented Model-Specific Case Studies
Root Cause: Broken ground wire on IAT harness branch near air box clip.
Verified Fix: Solder wiring repair and heat-shrink.
Technician Inspection & Testing Workflow
Check live data on scan tool: If IAT displays -40°F (-40°C), it confirms an OPEN circuit.
Unplug sensor. Jump signal wire to ground wire with a paperclip or fused jumper while watching scan tool. If IAT reading immediately flips to +284°F (+140°C), the wiring and ECM are 100% HEALTHY, proving the sensor itself has an internal open circuit.
Measure thermistor resistance across sensor pins with DMM: Expect 2,000–3,000Ω at room temperature. If infinite (OL), replace sensor.
Cost Breakdown
Tools & Parts Matrix
Diagnostic Questions & Answers
Why does my scanner say the air temperature is -40 degrees?
Because the circuit is broken (open). When zero current flows through the thermistor, the computer receives maximum 5.0 volts, which its lookup table translates to -40°F.