Summary
P0113 means the intake air temperature sensor signal indicates an extremely high temperature — usually because the circuit has an open connection, not because the air is actually that hot. The IAT sensor is a thermistor whose resistance drops as temperature rises; an open circuit mimics an extremely high temperature reading. The most common cause is an open circuit in the IAT wiring (40%), followed by a failed IAT sensor (30%) and a disconnected connector (20%).
Severity: Low
Safe to drive: Yes — the PCM uses a default air temp value
Repair cost: $0–$150 depending on cause
DIY difficulty: Easy
What does P0113 mean?
The intake air temperature sensor measures the temperature of air entering the engine. The PCM uses this data to fine-tune fuel mixture and ignition timing — cold air is denser and needs more fuel, while hot air is thinner and needs less. The IAT is a negative temperature coefficient (NTC) thermistor: its resistance is high when cold (around 100K ohms at -40°F) and low when hot (around 100–200 ohms at 250°F).
P0113 sets when the IAT signal voltage exceeds the PCM's high threshold — typically above 4.9V. Since the IAT circuit uses a pull-up resistor in the PCM, high voltage means high resistance, which means the PCM interprets it as extremely high temperature. In practice, this almost always indicates an electrical open circuit (disconnected sensor, broken wire, or corroded connector) rather than genuinely extreme intake air temperature.
The PCM substitutes a default air temperature value (usually around 70°F–100°F) when it detects the fault, so the engine continues running but fuel mixture adjustments for actual air temperature are disabled.