Intake Air Temperature Sensor 1 Circuit High
The Powertrain Control Module (PCM) detected that the Intake Air Temperature (IAT) sensor 1 signal voltage is higher than the expected normal operating range. This typically indicates an open circuit or a faulty sensor causing the computer to read an extremely cold default temperature, such as -40 degrees.
While the vehicle will usually still run, the engine computer will substitute a default temperature value, leading to poor fuel economy and drivability issues. It should be diagnosed and repaired soon to restore optimal engine performance and emissions.
Common symptoms
- Illuminated Check Engine Light
- Decreased fuel economy
- Rough idling or hesitation during acceleration
- Hard starting, especially in cold weather conditions
- Noticeable smell of unburned fuel from the exhaust
Likely causes
- Disconnected or loose IAT sensor electrical connector
- Broken or damaged wiring in the IAT sensor circuit causing an open circuit
- Faulty Intake Air Temperature (IAT) sensor
- Corrosion or bent pins in the IAT sensor connector
- Failed Mass Air Flow (MAF) sensor, if the IAT is integrated into the MAF assembly
- Faulty Powertrain Control Module (PCM), though this is rare
What to check before replacing parts
Perform a visual inspection of the IAT sensor, wiring harness, and connector.
Look for: Look for a disconnected plug, broken wires, chafing, or visible corrosion on the connector pins that could cause an open circuit.
Connect an OBD-II scan tool and monitor the live data for the IAT sensor.
Look for: Look for a fixed temperature reading of exactly -40°F (-40°C), which strongly indicates an open circuit in the sensor or wiring.
Disconnect the IAT sensor and measure the reference voltage at the harness connector using a multimeter.
Look for: Look for a reading of approximately 5 volts on the reference wire with the key on, engine off, confirming the PCM is sending the correct voltage.
Carefully install a jumper wire across the two terminals of the IAT harness connector and check the scan tool live data.
Look for: Look for the IAT reading on the scan tool to jump to its maximum high temperature (often around 284°F or 140°C); if it does, the wiring and PCM are good, and the sensor is faulty.
Measure the internal resistance of the IAT sensor itself using a multimeter.
Look for: Look for infinite resistance (OL) or a resistance value that does not match the manufacturer's specification for the current ambient temperature, indicating a failed sensor.
This page explains the generic P0113 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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