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An obstacle sensors unavailable warning does not always have the same cause. It may be related to the conditions at the location, an obstruction or a fault that requires support. Save the exact message and check the model before looking for a solution: vision systems and calibration processes vary between drones.
Distinguish an environmental condition from a persistent error
According to the DJI guidance on vision system errors, low light can make these systems unavailable. The manufacturer also identifies films, dirt and software or hardware problems among the possible causes of warnings. A message about insufficient lighting warrants a different interpretation from a code that requests repair.
If the drone is still on the ground, postpone take-off while you investigate. A brighter, unobstructed area may allow you to compare the warning, but it does not turn a persistent error into permission to experiment near trees or walls.
If you are already in flight, prioritise keeping clear of obstacles and landing safely. Avoid continuing through a narrow passage to find out whether the system starts responding again. Do not use the obstacle itself as a test target.
Check what your drone has
Consult the manual and identify which directions are covered by the sensors. Having downward positioning does not mean having lateral, forward and upward detection. You should also not transfer to another model the behaviour seen in a video about a different drone.
DJI publishes an introduction to obstacle systems with differences between equipment. Use it to locate your model’s system, and check the limitations and the relationship with the selected flight mode in the manual.
Inspection on the ground, with the equipment stationary
Switch off the drone before inspecting the sensors. Look for a transport film, a visible mark, a cover or an accessory placed near the field of view. Compare the accessory’s position with the manufacturer’s illustrations. Do not open the drone body to follow a calibration tutorial.
For cleaning, follow the instructions in the specific manual. Avoid trying solvents or rubbing an optical surface without knowing how it should be treated. If you find damage, stop troubleshooting at home and send photographs to support.
Record the result of each change. For example: the warning before removing a film, the warning afterwards and the lighting conditions in both observations. This comparison is more useful than changing the firmware, accessories and location all at once.
Calibration depends on the model
There is no universal procedure using DJI Assistant 2. In the sensor calibration instructions, DJI distinguishes models that support calibration in that programme from others that use automatic calibration through DJI Fly. The Mini 4 Pro appears in this second group.
Follow the current guidance in the app and the documentation for the equipment. An old tutorial may show a button that does not exist on your model. The absence of that button does not, by itself, show that the computer or drone is faulty.
Prepare a useful support request
Include the full code, photographs of the sensor areas, the flight mode and a description of when the warning appears. Say whether there was a fall, an impact during transport or a recent accessory installation. Keep observed facts and hypotheses separate.
A warning that persists in suitable conditions, or reappears after an impact, warrants technical assessment. Switching off a function to hide the warning does not resolve the source of the problem.
The pilot remains responsible for controlling the flight. The EASA explains the conditions of the open category, including visual contact and requirements concerning people. Sensors and automation do not replace these conditions or the applicable geographical zones.
Relate this diagnosis to loss of GPS or signal, IMU and compass and preserving flight records.
Illustrative image. No collision trials or sensor tests were carried out for this article.
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