A dashcam that just records is only half the job done. The other half is the G sensor, the small sensor that decides which clip is worth keeping the moment it matters most. One sudden jolt, and it locks that footage before anything can overwrite it, giving you proof exactly when you need it.
This guide breaks down how the G sensor works, why it protects your footage, and how to tune its sensitivity for Indian roads. Read on to get it set up right on your own dashcam.
What Is a G Sensor in a Dashcam?
A G sensor is a small motion sensor built into your dashcam that detects sudden changes in speed or direction, the kind that happen during a collision, a hard brake, or a heavy jolt. The moment it senses that kind of force, it tells the camera to lock the current video file.
Locked files are protected from the loop recording cycle. Everything else on the memory card keeps getting overwritten every few minutes, but the locked clip stays put until you move it off the card or delete it yourself. That is the entire job of a G sensor, catching the one moment your car needed proof and keeping it safe.
For a broader look at what to check before buying, see our complete dashcam buying guide.
How Does a Dashcam G Sensor Work?
Inside every G sensor sits a tiny accelerometer, the same basic technology used in a phone to know which way is up. It constantly measures force along three directions, forward and back, side to side, and up and down. Under normal driving, those readings stay within a narrow, predictable range.
The moment the accelerometer picks up a sudden spike well outside that range, a hard collision, a sharp swerve, even a bad pothole hit at speed, it sends a trigger to the camera's processor. The processor responds by locking the clip that was recording at that exact moment, along with a few seconds before and after it.
If you want the physics behind how accelerometers actually detect that kind of force, GeeksforGeeks has a clear breakdown of the working principle.
Why the G Sensor Is the Feature That Saves Your Footage
Loop recording is what makes a dashcam practical for daily driving. It keeps recording in a continuous loop, overwriting the oldest footage once the memory card fills up. You never have to manage storage yourself. Our loop recording guide explains how that loop works in detail.
But loop recording has one flaw on its own. If nothing stops it, the exact clip you need after an accident gets overwritten within minutes, sometimes before you have even pulled over. The G sensor is the fix. It watches for the one moment that matters and pulls it out of the loop before it disappears.
If you're running a 3 channel dash cam setup, the same trigger locks all three video streams together, front, cabin, and rear, not just one. That way an accident clip stays complete across every angle instead of losing the two feeds that didn't happen to be the "main" channel.
Tuning G Sensor Sensitivity for Indian Roads
On Indian roads, potholes and speed breakers are the biggest challenge for a G sensor. A dip or a bump taken at normal speed can produce almost as much force as a minor collision, and a sensor set to high sensitivity will lock a clip every time. A few dozen locked clips a day means your memory card fills up with junk footage instead of the recording you actually want to keep.
The fix is adjusting sensitivity in your dashcam's app, GoLook for the X300 and X600, Viidure for the X700 and X900. Most models offer three levels, low, medium, and high.
|
Sensitivity |
Best For |
|
Low |
City driving, potholes, speed breakers, stop and go traffic |
|
Medium |
Mixed city and highway driving |
|
High |
Highway driving, parking areas, situations where you want every jolt captured |
Most owners driving in Indian cities do well starting on low or medium and adjusting from there once they see how many clips get locked in a normal week.
G Sensor and Parking Mode
A parked car is still vulnerable, someone could reverse into it, scrape it while passing, or try to break into it. Parking mode uses the G sensor to catch exactly that kind of moment while the car is off.
When the dashcam is in parking mode, most of its systems power down to save battery, but the G sensor keeps watching. The moment it detects an impact, it wakes the camera, records the incident, and locks the clip automatically. This only works with continuous power from a hardwire kit, since a parked car's accessory power is usually switched off.
About the author
Bhavesh Kumar, Head of Product & Customer Success at nextro. He works directly with customers on dashcam setup, footage recovery, and insurance claims, and writes about what actually holds up in Indian driving conditions.
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