IAT Sensor (D/C) Open/Short
Your intake air temperature sensor has an electrical break or short circuit, like a frayed wire preventing proper signal. The engine computer can't read how hot the incoming air is, so it can't adjust fuel mixture correctly.
The ECU monitors resistance changes from the IAT sensor as intake air temperature varies. The sensor uses a thermistor that changes resistance based on temperature; the ECU converts this to a voltage signal. An open or short circuit breaks this signal pathway entirely.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| IAT Sensor Voltage | 0.5–4.5 V (varies with temperature) | Below 0.1 V or above 4.9 V (open/short detected) |
| Signal Continuity | Continuous valid resistance change | No signal or constant maximum/minimum resistance |
Code P1115 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, P1115 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.