Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage
Your intake air temperature sensor is sending an unusually high voltage signal to the engine computer, causing it to think the air is hotter than it really is. Think of it like a thermometer that occasionally reads way too high, confusing your engine's fuel calculations.
The IAT sensor is a thermistor that changes resistance based on air temperature, sending a voltage signal to the ECM. The ECM expects voltage within a specific range; when it detects intermittently high voltage (indicating artificially cold air reading), it triggers the fault. This affects fuel trim and ignition timing calculations.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| IAT Sensor Voltage | 0.5-4.5V (approximately -40 to 125°C) | Intermittent spikes above 4.7V or open circuit condition |
| IAT Signal Rate of Change | Gradual transitions | Rapid unexplained voltage jumps |
Code P1116 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1116 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.