C4001 sensors have limited range / not working
Tariq.Muthaliph 2025-11-07 14:18:50 250 Views2 Replies first i purchased 2 sensors to test the sensors, they worked very well in indoor environment. so i purchased a few more to place them in different locations, however the sensors i puchased later were not working properly, they only detect range < 1 to 2m. what is the reason, i tried changing thresholds, however they did not work, what can i do to get them working.
I recently bought two C4001 radar modules and tested them side by side with the official DFRobot_C4001 library and example sketches.
My setup is very straightforward: Arduino Mega2560, same wiring, same power supply, same sketch.
Module A: Works exactly as expected. It detects targets reliably up to several meters (3–5 m and beyond)Module B: Under identical conditions, it only detects targets up to about 80 cm. No matter how I change the parameters (setDetectThres, thresholds, min/max distance, sensitivity), the detection range never improves.I tried:
Different Serial ports (Serial1, Serial2, Serial3 on the Mega)Different cables and solderingAdjusting thresholds (min/max up to 2000 cm, thres down to 3–5)Power supply filtering (capacitors on VCC/GND)The results are always the same: one sensor works fine, the other is limited to ~80 cm.
From my perspective this looks like a hardware defect in the RF frontend of the short‑range module. I’ve seen other users here report similar issues, so I wanted to share my experience and confirm that this is not a software or wiring problem.
Has anyone else had the same situation? Did you solve it only by replacing the module?
Macy7 These ultrasonic sensors are very sensitive to supply voltage and current stability.
Check with a multimeter: you should have a stable 5 V (or rated voltage) at the sensor pins even when it’s operating.
Some clones fail above 4.8 V or under 5.0 V, affecting the range.
ahsrab.rifat 