Intake Air Temperature Sensor 1 Circuit High

What it means

The engine computer has seen an intake air temperature (IAT) signal voltage above the highest acceptable level, so it reads illogically cold air. The most common cause is an open circuit, such as a connector left unplugged after an air filter change or a broken wire.

Related codes: P0110P0111P0112P0114P0102P0118

Symptoms4

• Check engine light on.
• Very low air temperature reading on the scan tool that does not match the weather.
• Slightly higher fuel consumption.
• Often no other noticeable symptom.

Possible causes5

• Unplugged IAT or MAF sensor connector, especially after air filter service.
• Open circuit in the signal or ground wire.
• Corroded or loose connector pins.
• Internal open circuit in the IAT sensor.
• Failed MAF sensor when the IAT sensor is built into it.

How to diagnose5

1. First make sure the sensor connector is firmly plugged in, especially if the code appeared after recent service.
2. Watch the IAT reading on a scan tool; a reading stuck at the lowest possible value means an open circuit.
3. Bridge the signal and ground pins in the connector with a jumper wire; if the reading jumps to the highest value, the wiring is good and the sensor is faulty.
4. Check continuity of the signal and ground wires to the computer.
5. Measure sensor resistance and compare with the manufacturer table.

How to fix5

1. Reconnect the unplugged connector.
2. Clean or replace the connector pins.
3. Repair the broken wire.
4. Replace the IAT sensor, or the MAF sensor if it is built in.
5. Clear the codes and confirm the reading is close to outside air temperature.

The fix is often just reconnecting a connector at almost no cost; it rises when a MAF sensor with a built-in IAT sensor is needed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions