Your fuel temperature sensor isn't sending the right signal to the engine computer, like a broken thermometer that can't tell how hot the fuel is. This prevents the engine from adjusting fuel mixture properly based on fuel temperature.
The ECU monitors voltage from the fuel temperature sensor (typically a thermistor) to measure fuel temperature and adjust injection timing and duration. The sensor resistance changes with temperature, and the ECU expects a voltage signal within a normal operating range. If voltage is out of range or absent, a circuit malfunction code is triggered.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor voltage | 0.5V - 4.5V (varies by vehicle) | Below 0.2V or above 4.8V, or no signal |
| Temperature reading | -40°C to 125°C (-40°F to 257°F) | Out-of-range reading or implausible value |