P0113: Intake Air Temperature (IAT) Sensor 1 Circuit High Input
May cause incorrect air‑fuel mixture resulting in rough idle, poor fuel economy, and reduced performance; vehicle often still drivable but not optimal.
Overview
P0113 indicates that the IAT sensor circuit is reporting a voltage above expected range (high input), often due to sensor or wiring fault, leading to incorrect air temperature readings and impacting air‑fuel mixture management.
Common Symptoms
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation
- Difficulty starting or inconsistent engine performance
Most Common Causes
Sensor may be internally failed or stuck at high resistance leading to high voltage signal.
Damaged, corroded, or loose wiring/connectors to IAT sensor often triggers high input signal.
In vehicles with IAT built into MAF, failure of MAF assembly can present P0113.
Rare cause; PCM may incorrectly interpret signal or lose reference voltage.
Diagnostic Steps
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Connect OBD‑II scan tool and confirm P0113 code; observe live IAT sensor voltage and temperature readings.Expected: IAT voltage above normal range or unrealistic temperature reading compared to ambient.Interpretation: High input confirms the circuit issue; proceed to inspect sensor/wiring.
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Visually inspect IAT sensor, connector, and wiring for damage, corrosion, or loose connections.Expected: Clean, secure connectors with intact wiring.Interpretation: Any damaged or corroded components should be repaired or replaced.
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Use a multimeter to check reference voltage at sensor harness (approx ~5V) and continuity/ground.Expected: Stable 5V reference and good ground continuity.Interpretation: Missing voltage or ground indicates wiring/PCM issue.
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Test IAT sensor resistance vs. temperature with heat source and compare to spec.Expected: Resistance decreases with rising temperature.Interpretation: If sensor shows open circuit or incorrect resistance, replace sensor.
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After repairs, clear codes and test drive to confirm code does not return.Expected: Code remains cleared and IAT readings reflect ambient conditions.Interpretation: Successful repair verified.
Repair Solutions
Common fix when sensor fails; cost varies if integrated with MAF assembly.
Includes cleaning corrosion, soldering, or replacing harness sections.
Often required on vehicles where IAT is built into MAF sensor.
Rare; only if all wiring/sensor tests are good and faults persist.
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Assuming air filter or unrelated engine issue is primary cause without testing IAT circuit
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