Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit description
Inlet temperature sensor, which is built into the intake air flow meter sub-assembly, detects intake air temperature. The resistance of the thermistor built into the inlet air temperature sensor changes as the intake air temperature varies. The lower the intake air temperature, the greater the thermistor resistance, and the higher the intake air temperature, the lower the thermistor resistance. The inlet air temperature sensor is connected to the engine control computer. The 5-V power supply voltage is supplied from THA terminal of the computer, and grounded in the computer via the resistor integrated into the inlet air temperature sensor. Therefore, since the resistor and the inlet air temperature sensor are connected in series, the resistance changes as the inlet air temperature changes, and the potential at the THA terminal also changes. Based on this signal, the engine control computer increases the fuel injection amount to improve driveability when the engine is cold.
| DTC No. | DTC detection condition | Suspected parts |
|---|---|---|
| P0111 | Difference between maximum and minimum values in inlet air temperature sensor voltage is less than 0.02 V. (2 trips detection logic) |
Inlet air temperature sensor (integrated into intake air flow meter sub-assembly) |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.