Fuel Level Sensing
The fuel-level input converts an analog sender voltage into a percentage with an eight-point calibration curve. In TunerStudio, open Sensors > Fuel level sensor, assign Input channel, and edit the Fuel Level voltage-to-percentage curve (fuel-level dialog). The curve voltage points must be ascending.
The sensor subscribes to the ADC with a 2 Hz low-pass filter and has a 500 ms timeout (sensor initialization). This smoothing reduces sender and fuel-motion noise but also makes the displayed level respond slowly.
Calibration
Use the vehicle manufacturer's sender curve, or obtain voltage-versus-level points from a safe bench sweep of the sender with a board-compatible interface. Enter monotonic voltage bins and the corresponding percentages, including useful intermediate points if the tank shape is nonlinear. Verify that the curve is not extrapolating a flat or reversed section. Do not use the analog temperature input circuit as an assumed fuel-sender interface unless the board documentation confirms that its bias circuit is suitable.
Diagnostics and wiring
Compare Fuel level with Raw fuel level. A raw voltage that remains sensible while percentage is wrong points to the curve; a missing or stuck raw voltage points to the sender, supply, ground, input channel, or board interface. The status channel uses getOrZero, so a timed-out sensor can appear as 0% rather than as an explicit error (status publication).
This revision has no fuel-level entry in the normal Sensor Checker list, so a 0% display is not by itself proof of an empty tank. Select the input from the exact board target. For a Universal 112 v1.2, use one of the documented analog-voltage pins in the revision-specific pinout.