Intake Air Temperature Sensor 1 Circuit
The P0110 code indicates a malfunction in the Intake Air Temperature (IAT) Sensor 1 circuit. The Engine Control Module (ECM) sets this code when it detects a voltage signal from the IAT sensor that falls outside the expected normal operating range.
While the vehicle will usually still drive, the engine may run rich or lean, leading to poor fuel economy and potential long-term catalytic converter stress. It should be diagnosed and repaired soon to restore optimal engine performance.
Common symptoms
- Illuminated Check Engine Light
- Decreased fuel efficiency
- Rough idling or hesitation during acceleration
- Difficulty starting the engine, especially in cold weather
- Slight decrease in overall engine power
Likely causes
- Faulty Intake Air Temperature (IAT) sensor
- Damaged, corroded, or loose wiring/connector at the IAT sensor
- Open or short circuit in the IAT sensor wiring harness
- Dirty or contaminated IAT sensor element
- Faulty Engine Control Module (ECM) (rare)
What to check before replacing parts
Perform a visual inspection of the IAT sensor and its electrical connector.
Look for: Broken wires, backed-out pins, or heavy corrosion that would cause a poor electrical connection.
Monitor the IAT sensor reading using a scan tool's live data stream.
Look for: An extreme temperature reading, such as -40°F (indicating an open circuit) or over 280°F (indicating a short circuit), that does not match ambient conditions.
Measure the IAT sensor's internal resistance using a digital multimeter.
Look for: Resistance values that do not match the manufacturer's specified temperature-to-resistance chart for the current ambient temperature.
Check for the 5-volt reference signal at the IAT sensor connector with the key on, engine off.
Look for: A steady 5-volt signal from the ECM; if missing, there is a wiring issue or ECM fault.
Test the ground circuit at the IAT sensor connector.
Look for: Good continuity to ground (low resistance); high resistance indicates a wiring issue between the sensor and the ECM.
This page explains the generic P0110 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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