P1116 IAT Sensor Intermittent High Voltage
The P1116 code indicates that the engine control module (ECM/PCM) has detected an intermittent, abnormally high voltage signal from the intake air temperature (IAT) sensor circuit. The IAT sensor is a negative temperature coefficient (NTC) thermistor, meaning its resistance decreases as temperature rises. A high voltage reading typically points to excessive resistance or an open in the return circuit, which the ECM interprets as an unusually low intake air temperature. The intermittent nature suggests sporadic faults in wiring, connectors, or the sensor itself, making diagnosis challenging since the problem may not be present during initial inspection.
01. Most Common Causes
- Faulty or internally deteriorated IAT sensor
- Corroded, oxidized, or loose connector pins at the IAT sensor
- Intermittent open or short to reference voltage in the IAT circuit wiring
- Excessive resistance in the sensor ground circuit
- Harness damage from chafing, heat, or vibration
- Intermittent internal failure of the PCM/ECM analog-to-digital converter channel
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Possible poor fuel economy or drivability issues (rough idle, hesitation) due to incorrect air-fuel mixture
03. Step-by-Step Diagnosis
Scan for codes and record freeze frame data to capture conditions when the fault occurred.
Visually inspect the IAT sensor connector and wiring for corrosion, damage, or loose connections.
Monitor IAT sensor voltage with a scan tool while gently wiggling the harness to reproduce the intermittent fault.
Compare IAT sensor resistance to temperature using a multimeter and manufacturer specifications.
Check for voltage drop in the sensor ground circuit and verify reference voltage (typically 5V) at the sensor connector.
1. Frequently Asked Questions
Is it safe to drive?▼
Yes, but the vehicle may experience reduced fuel economy and drivability issues. It is recommended to diagnose and repair the fault soon to prevent potential damage to other components.
How much does it cost to fix?▼
Typically between $100 and $300, including parts and labor. The IAT sensor itself is inexpensive ($20-$50), but diagnosis time and potential wiring repairs can increase the cost.