For a ratiometric measurement, the relationship between signal and reference matters. A small voltage change at a sensor is not always a change in the physical quantity being measured.
Interpreting the evidence
Compare the sensor supply, reference and signal under the same conditions, using the correct circuit information. If several readings move together, look for a shared electrical influence before treating them as separate sensor failures. The ECU’s interpreted value should be checked alongside measured voltages.
Keep this evidence
Include which other sensors share the supply and whether their readings change together.
Do not assume every five-volt sensor is ratiometric or uses the same transfer function. The fitted device determines the correct interpretation.
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Technical background from Texas Instruments. The referenced design explains the principle; the vehicle-specific procedure determines the repair.
Related reading — SENT calibration timing and a waveform that will not decode. Browse all vehicle-electronics diagnostic notes or return to the repair library.