- Phones and tablets
- Drones
IMU calibration required
DJI drone IMU calibration required: inertial sensor data error
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
If your DJI app prompts IMU calibration required, IMU calibration failed, or Error Code 40021, ensure at least 50% battery, fold the arms on Mavic series drones, and place the aircraft on a level, dry surface before calibrating in DJI Fly, DJI GO 4, or your goggles.
Safety first
Stop and check this first
- Do not attempt IMU calibration with less than 50% battery or on an unlevel or damp surface, and follow every on-screen directional placement carefully because skipping a position can result in calibration failure.
Safe checks you can perform
- Prepare battery charge, Mavic arms, and a level dry surface
- Run IMU calibration in DJI Fly, goggles, or DJI GO 4
- Restart the aircraft after failure or complete Error Code 40021 steps
Leave these tasks to a qualified professional
- Do not attempt this professional task: Complete multi-direction IMU calibration under DJI pre-calibration rules
- Do not attempt this professional task: Retry after an aircraft restart and submit a DJI repair request if unresolved
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Complete multi-direction IMU calibration under DJI pre-calibration rules
What they doThe technician confirms at least 50% battery, folds the arms on Mavic series drones, removes the microSD card when addressing Error Code 40021, and positions the aircraft on a level, dry surface in each direction prompted by DJI Fly, DJI GO 4, or the goggles.
They must show youthe pre-calibration setup on a level dry surface and the on-screen IMU calibration sequence completing.
In writingaircraft model, battery level, whether a microSD card was removed for Code 40021, and the IMU calibration outcome.
Retry after an aircraft restart and submit a DJI repair request if unresolved
What they doIf IMU calibration fails or Error Code 40021 persists after both gimbal and IMU calibration, the professional restarts the aircraft, repeats the procedure, and submits an online repair request to send the drone to DJI for testing.
They must show youthe calibration retry after restarting the aircraft and the resulting sensor status in the app.
In writingcompleted IMU and gimbal calibration attempts and the DJI online repair request reference if the fault remains.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Prepare battery charge, Mavic arms, and a level dry surface
- Who:
- you, preparing your DJI aircraft and linked remote controller on the ground.
- How:
- power on the aircraft and link it to the remote controller, verify that the battery level is at least 50%, remove any installed microSD card if Error Code 40021 appeared, fold the arms for Mavic series drones, and set the aircraft on a level and dry surface.
- Result that matters:
- satisfy DJI's pre-calibration preparations before starting the multi-position IMU routine.
- If battery charge is at least 50% and the aircraft is prepared on a level dry surface:
- open the calibration menu for your model.
- If the battery is below 50%:
- recharge before attempting IMU calibration.
- Evidence to keep:
- recorded battery percentage, arm state, and confirmation of a level and dry surface.
Evidence: IMU Calibration Guide · How can I resolve the issue if the app prompts Gimbal IMU data error (Error Code 40021) during flight
Run IMU calibration in DJI Fly, goggles, or DJI GO 4
- Who:
- you, using the app or goggles specified for your DJI drone series.
- How:
- for DJI Air Series, DJI Neo, DJI Mini Series, and DJI Mavic 3 Series in DJI Fly, tap ··· > Safety > Sensor > IMU > Calibration; for DJI FPV and DJI Avata Series, power on the goggles and go to Setting > Safety > Aircraft IMU Calibration > Start; for Mavic 2, Phantom 4, and Spark, use DJI GO 4.
- Result that matters:
- place the aircraft in each direction according to the on-screen instructions until calibration completes.
- If all directional steps finish and IMU calibration succeeds:
- keep the completion record.
- If IMU calibration fails or Error Code 40021 was reported:
- proceed to the restart and gimbal calibration step.
- Evidence to keep:
- menu path used and the on-screen completion or failure prompt.
Evidence: IMU Calibration Guide
Restart the aircraft after failure or complete Error Code 40021 steps
- Who:
- you, following up on an IMU calibration failure or Error Code 40021 prompt.
- How:
- if Error Code 40021 appeared, perform both gimbal calibration and IMU calibration with the microSD card removed; if IMU calibration fails, restart the aircraft and go through the calibration steps again.
- Result that matters:
- confirm whether restarting the aircraft and repeating the required calibrations resolves the IMU data error.
- If the warning clears after restarting and recalibrating:
- retain the result before flying.
- If the issue remains after restarting and repeating the steps:
- send your drone back to DJI via an online repair request.
- Evidence to keep:
- post-restart calibration outcome and screenshot of any persistent IMU or 40021 warning.
Evidence: IMU Calibration Guide · How can I resolve the issue if the app prompts Gimbal IMU data error (Error Code 40021) during flight
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Phones and tablets
- Brand
- DJI
- Product type
- Drones
Known code variants
- Código de error 40021
- Error Code 40021
- Error de calibración de la IMU
- Es necesario calibrar la IMU
- Gimbal IMU data error
- IMU calibration failed
- IMU cannot be calibrated
- No se puede calibrar la IMU
What it means
DJI's IMU Calibration Guide and Error Code 40021 support article cover DJI Mini Series (such as Mini 3 Pro), DJI Air Series, DJI Mavic 3 Series, DJI Neo, DJI Avata Series, DJI FPV, Mavic 2 Series, Phantom 4 Series, and Spark. They attribute these alerts to an IMU data error resolved by placing the aircraft in the orientations shown on screen. Other model families may differ, and this prompt alone never proves that the IMU or any other component is defective.
Warnings and stop conditions
- Mediumsource verified
Do not attempt IMU calibration with less than 50% battery or on an unlevel or damp surface, and follow every on-screen directional placement carefully because skipping a position can result in calibration failure.
Evidence: IMU Calibration Guide
Symptoms and causes
Probable causes · in order
- Aircraft inertial measurement unit (IMU) data errorCommon
DJI's IMU Calibration Guide states that an IMU data error triggers the in-app prompts requiring or failing IMU calibration.
Evidence: IMU Calibration Guide
- Uneven surface, unfolded Mavic arms, or missed orientation stepsPossible
Failing to fold the arms on Mavic series drones, placing the aircraft on an unlevel or damp surface, or not following the on-screen directional placements can cause calibration failure.
Evidence: IMU Calibration Guide
- Gimbal IMU data error (Error Code 40021) during flightPossible
When Error Code 40021 appears in flight, DJI directs performing both gimbal calibration and IMU calibration and advises removing any installed microSD card beforehand.
Evidence: How can I resolve the issue if the app prompts Gimbal IMU data error (Error Code 40021) during flight
Virtual technician
Does IMU calibration required still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
DJI · 2026 · official_doc
- 2
DJI · 2026 · official_doc
- 3
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