Answer: A wrong 4‑20 mA reading is almost always a calibration, wiring or range-mapping issue rather than a sensor fault. Work through these in order:
- Recalibrate against the real receiver. Internal resistance differs between display meters, PLC cards and data loggers; run Bluetooth – 4‑20 mA Output Calibration – Current Calibration with the actual meter connected.
- Check the installation height and range mapping. A wrong installation height or 4 mA / 20 mA endpoint shifts the whole output by a fixed offset; confirm Water Depth = Installation Height – Empty Distance.
- Measure the loop current in series with a multimeter and compare it with the value reported by the upper-computer software. If the loop current is correct but the display is wrong, the fault is in the receiving device or its scaling.
- Check supply voltage and wiring. Voltage drop over long cable runs, loose terminals or missing loop power all distort the current; keep the supply within specification and use thicker-gauge wire on long runs.
- Confirm the level reading itself is stable. If the radar is locking onto a false echo (wall, foam, secondary echo), the 4‑20 mA output will faithfully follow that wrong value — fix the measurement first.
If the output is still off after these checks, send us the loop current measurement, an installation photo and the echo spectrum; our support team will diagnose it with you.
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