You had a dashcam running, an incident happened, and the file was gone. This is the most frustrating failure in the whole category, and it is almost always caused by a misunderstanding of loop recording and event locking. This article explains how these two features interact, how to configure them so critical clips survive, and the mistakes that quietly overwrite the footage you needed.
How loop recording works
A dashcam does not record one endless file. It splits video into short segments, typically one, three, or five minutes each. When the card fills up, the camera deletes the oldest segment to make room for the newest. This loop is what lets a small card run indefinitely without you managing files.
The catch is in that word “deletes.” Unless a segment is protected, it is fair game to be overwritten. On a busy card that fills in a day or two, your incident footage can be gone within 48 hours if you never retrieve or lock it.
What the G-sensor and event lock actually do
The G-sensor is an accelerometer. When it detects a sudden jolt above a set threshold, the camera flags the current segment as an “event” and moves it to a protected folder so the loop cannot overwrite it. On a Cali Camera GPS unit this usually shows as a lock icon on screen, and the file lands in an “Event” or “RO” folder separate from normal footage.
Why sensitivity matters both ways
Set the G-sensor too low (very sensitive) and every pothole and speed bump creates a locked file. The protected folder fills, and here is the trap: once that folder is full, some cameras stop locking new events, or begin overwriting old locked files. Set it too high (not sensitive enough) and a genuine low-speed collision may not trigger a lock at all. The goal is a middle setting that catches real impacts but ignores normal road roughness.
Loop length: short vs. long segments
| Segment length | Advantage | Drawback |
| 1 minute | Easy to copy and share; less data lost if one file corrupts | More files to manage; an event may span two clips |
| 3 minutes | Balanced for most drivers | Minor: slightly larger files to transfer |
| 5 minutes | Fewer files | A corrupted file loses more footage; harder to isolate a moment |
For most drivers, one to three minutes is the practical sweet spot, because an impact can happen right at a segment boundary and you want both sides preserved.
A real scenario
A driver is rear-ended at a red light. The jolt is real but gentle, and his G-sensor is set to low sensitivity, so no event lock triggers. He assumes the footage is safe and keeps driving for two more days of city traffic. By the time he checks, the loop has recycled the card and the clip is overwritten. Had he either raised sensitivity slightly or pulled the card that same evening, the evidence would have survived. The lesson: after any incident, stop and protect the file immediately.
Common mistakes and how to fix them
- Relying only on the G-sensor. It can miss slow-speed or glancing impacts. Fix: after any event, manually press the lock/emergency button, or power down and remove the card.
- Never clearing the event folder. A full protected folder can stop new locks. Fix: offload and clear locked files periodically.
- Sensitivity set to maximum. It fills the protected folder with pothole clips and buries the real event. Fix: use a medium setting and test it over a week.
- Assuming a locked file is backed up. It is still only on the card. Fix: copy important events to your phone or computer promptly.
- Leaving the card in after an incident. Continued driving keeps the loop running. Fix: for a serious event, remove the card and store it.
Action steps to protect critical footage
- Set loop segment length to one to three minutes.
- Set G-sensor sensitivity to medium, then adjust after a week of real driving.
- Learn where your emergency/lock button is and press it after any incident.
- Check the size of the event folder monthly and clear old locked clips.
- After a serious incident, power down and remove the card the same day.
- Back up locked events to another device before your routine format.
Conclusion and next step
Loop recording keeps your camera running forever; event locking keeps the moment that matters. The next step is to open your camera’s menu today, confirm the G-sensor is on at a sensible level, and press the lock button once so you know exactly where it is before you ever need it.
FAQ
If loop recording overwrites old files, is my incident automatically saved?
Only if the segment was locked, either automatically by the G-sensor or manually by you. Unlocked footage can be overwritten within a day or two on a busy card, so protect important clips right away.
What G-sensor sensitivity should I use?
Start at medium. If potholes and speed bumps constantly create locked files, lower it one step. If you doubt it would catch a real bump, raise it. Test over a week of normal driving.
The event folder is full. What happens now?
Behavior varies by model: some cameras stop locking new events, others begin overwriting the oldest locked files. Either way you risk losing protection, so clear the folder regularly.
Can I lock a clip myself while driving?
Yes. Most dashcams have an emergency or lock button that protects the current segment on demand. Know where it is so you can press it safely after an incident.