P0113 - Intake Air Temperature Sensor 1 Circuit High Input
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0113 is set when the engine control unit (ECU) detects a voltage signal from the Intake Air Temperature (IAT) sensor that is higher than the calibrated threshold (typically above 4.5V to 4.8V). The IAT sensor is an NTC (Negative Temperature Coefficient) thermistor, where resistance decreases as temperature increases. A high voltage signal indicates high resistance or an open circuit, which the ECU interprets as an extremely cold intake temperature (often below -40°C). This data is critical for the speed-density or mass air flow calculations to determine fuel trim and ignition timing. When this code is active, the ECU usually ignores the sensor and defaults to a fail-safe lookup table value.
Possible Causes
Faulty IAT sensor (internal open circuit/high resistance)
Loose connection or corrosion in the sensor connector
Wiring break in the signal or ground circuit to the ECU
Internal ECU failure or incorrect reference voltage
Symptoms
Recommended Solution
- Visual Inspection: Check wiring and the connector at the air filter box or intake manifold. Look for frayed wires or corroded pins.
- Data Analysis: Use a scan tool to view 'Live Data' for IAT. If it reads -40°F/°C, the circuit is open.
- Voltage Test: Unplug the sensor and measure between reference and ground on the harness side. You should see a steady 5V reference.
- Resistance Test: Measure resistance across the IAT sensor pins. At 68°F (20°C), resistance should be approx. 2000-3000 Ohms. If it shows infinite resistance (OL), replace sensor.
- Replacement: If 5V is present but the sensor returns incorrect resistance, replace the IAT sensor (often part of the MAF sensor).
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
Do you also have
other fault codes?
See how P0113 connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.