How to inspect an SD card used in a dashcam

Your dashcam may show an error, skip clips, or stop saving footage even though the SD card still appears in the menu. A card that has recorded for months can slow down, become unreliable, or simply fill up with locked files that loop recording will not remove.

Inspect the footage first, then check the card's read and write performance with the USB & SD Speed Test. A speed result is useful, but it cannot prove that a card is healthy or that it will keep recording reliably in your specific dashcam.

Inspect the card safely

1. Turn off the dashcam before removing the card. If a recent clip matters, stop driving and power the camera down cleanly so it can finish writing the file.
2. Unlock the card if its adapter has a write-protect switch, then insert it in a computer's card reader. Open a few recent clips and check that they play from beginning to end. Look at the file dates and sizes too.
3. Back up any footage you may need before testing or changing the card. Dashcams often overwrite old recordings, and some clips are protected from loop recording. Do not rely on the card as the only copy of important evidence.
4. Open the USB & SD Speed Test and choose the SD card or the card reader when prompted. Follow the test's on-screen instructions. Compare its read and write results with the speed requirements in your dashcam manual or the card manufacturer's specifications.

Use the same reader and computer for comparisons. A slow adapter, USB port, or hub can affect the result, so a low score does not automatically mean the card itself is bad. If the card contains footage you have not backed up, do not run a test that writes to it until those files are safe elsewhere.

What the result means

Recent clips play normally and speed meets the camera's needs

The card is behaving as expected in this check. Keep an eye on new recordings and make sure the dashcam reports that it is recording. A brief speed test cannot guarantee that the card will avoid errors during hours of continuous writing, especially in heat.

Clips are missing, damaged, or will not play

The card may have failed to finish writing, the file system may be damaged, or the dashcam may not have saved the clips you expected. Try another card reader or computer before concluding that the files are lost. If the clips are important, stop using the card and avoid formatting it, since new writes may overwrite recoverable data.

Write speed is below the dashcam's requirement

The card or the reader may be too slow for the camera's video settings. Check the exact card speed class and minimum sustained write speed required by the dashcam maker. A high advertised read speed does not guarantee equally fast writing.

Results vary widely between runs

The card reader, port, background activity, or test method may be affecting the measurement. Repeat the check with the same setup, then try a different reader. A single unusually low result is not enough to identify a failing card.

What to do about recording problems

1. Check that the card is seated correctly. Remove it only after the dashcam is off, then reinsert it firmly. Check the card and slot for visible dirt or damage, and avoid touching the metal contacts.
2. Check available space and protected clips. A full card may stop recording if important clips are locked or loop recording is disabled. Copy any footage you need, then review the dashcam manual for its loop-recording and clip-lock settings.
3. Check the camera's recording settings. High resolution, a high frame rate, or multiple camera channels can require more writing speed. Compare the selected settings with the dashcam's card requirements. On the computer, use File Explorer › This PC on Windows 11 or Disk Utility on macOS to view the card and its available space, but do not erase or reformat it before backing up files.
4. Format the card in the dashcam only after backing it up. If the camera's manual recommends periodic formatting, use its own format option rather than choosing a file system at random on a computer. Formatting deletes the card's files, so copy important recordings first.
5. Test with a known-good, compatible card. Use a card type and capacity supported by the dashcam. If the replacement records normally, the original card is the likely cause. If both cards fail in the same way, check the camera, its power supply, and its settings.

When the card is probably worn out

SD cards used in dashcams are written to repeatedly, and their service life depends on the card, recording quality, temperature, and how often the camera is used. Repeated recording errors, corrupted clips, or a card that works briefly and then fails are stronger warning signs than one low speed result. Do not use a questionable card for footage you may need after an accident.

Replace a card that continues to fail after testing it in a compatible reader and dashcam. Choose a card intended for continuous recording, confirm its capacity and speed requirements against the camera manual, and keep a backup of important clips. For guidance on checking a card before putting it into a dashcam, see how to check an SD card before using it in a dashcam.

Why a speed test is only one check

A speed test measures transfer performance under its test conditions. Dashcam recording is different: the camera writes continuously, may create multiple files, and may operate in a hot windshield area. A card can show a reasonable result during a short test and still develop errors later. The best practical check combines the dashcam's stated requirements, readable recent clips, and reliable recording over time.

Copy any footage you want to keep before formatting, testing writes, or putting the card back into a camera that may overwrite old files.