Why did I get a Sentry Mode alert on my phone but there is no video on the USB drive?

Because the alert and the recording are separate. Tesla's manual states that when Sentry Mode detects a security event without a USB drive plugged in, the car alerts you through the mobile app without any camera recordings. The notification proves the car detected something; only a properly formatted drive in a recording-capable port, with Dashcam enabled and free space available, produces a clip. If the car wrote the clip and later deleted it to free space, ClipSalvage can scan the drive for it and recover what it finds.

Can ClipSalvage recover a Sentry clip the car never recorded?

No. Recovery software reads what was written to the drive, including clips that were later deleted or lost to a format. If Sentry never wrote the clip, there is nothing on the drive for any tool to find, ClipSalvage included. A free scan shows quickly which case you are in.

Does Sentry Mode record if Dashcam is turned off?

No. Tesla's manual states that Dashcam must be enabled for Sentry Mode to work and that the car does not record videos when Dashcam is Off. Check Controls › Safety › Dashcam before anything else.

Which USB port records Sentry Mode footage?

The USB-A port in the glovebox, or a front port in the center console on cars without one. Tesla's manual says rear ports only charge devices, and that on some vehicles made after about November 2021 the center-console USB-C ports also only charge, so the glovebox port is the one to use.

Tesla Sentry Mode Is On but Not Recording to the USB Drive

A Sentry Mode alert doesn't prove a clip was saved: Tesla can alert you without recording if no usable USB drive is installed, and when the drive runs low on space the car deletes its oldest Sentry clips. If the clip was written and later deleted, ClipSalvage can scan the USB drive for it and recover what it finds; if the car never wrote it, no software can.

Never written, or written and then gone?

These are different problems with different fixes. This page is about clips that were never written — the car detected an event but nothing reached the drive. If the clip was there and has since disappeared (the drive filled up and the car deleted older Sentry events, or the drive was formatted), that footage may still exist on the flash, and a ClipSalvage scan can look for it: read why Sentry events go missing from the USB drive instead.

An alert is not a recording

Tesla's manual lists what Sentry Mode does when it detects a threat: it pulses the headlights, sounds the alarm, shows a message on the touchscreen, alerts you in the mobile app — and "saves footage of the event to a USB drive (if installed)". That last qualifier is the whole story. The manual then says it outright: when Sentry Mode is enabled and a security event is detected without a USB drive plugged in, the vehicle alerts you through the mobile app without any camera recordings.

So the phone notification proves the car's sensors fired. It does not prove a clip was written. The recording depends on a second set of conditions — a properly formatted drive, in a port that can record, with Dashcam enabled and space free — and every case on this page is one of those conditions failing quietly while the Sentry icon stays red.

What Tesla says Sentry Mode needs before it can record

All of the following come from Tesla's owner's manual (the Sentry Mode, Dashcam and USB-drive pages, linked at the end). The car needs every one of them at the moment of the event:

Dashcam enabled. "Dashcam must be enabled for Sentry Mode to work", and the car "does not record videos when Dashcam is Off". The setting is Controls › Safety › Dashcam.
Sentry Mode actually enabled at that location. With Exclude Home, Exclude Work or Exclude Favorites turned on (Controls › Safety › Sentry Mode), Sentry does not automatically enable within roughly 500 metres of the saved location. Turning it on by hand from the touchscreen or the app overrides the exclusion until the next drive. When it is enabled, the Sentry Mode icon in Controls is red.
Battery at 20% or more. Sentry Mode turns off below 20% and the app sends a notification when it does.
A properly formatted USB drive in a port that can record. The manual is specific about the port: use the USB-A port in the glovebox if the car has one, otherwise a front port in the center console. Rear ports "can only charge devices", and on some vehicles built after about November 2021 the center-console USB-C ports also only charge.
Free space on the drive. "When the USB drive runs out of storage space, video footage can no longer be saved." When space becomes limited the car deletes the oldest Sentry clips to make room for new ones — which is the boundary between this article and the one on vanishing events.

Five checks on the touchscreen

With the car in Park, in this order:

Open Controls and look for the icons. The manual says that once a drive is recognised, "ensure icons for Dashcam and Sentry Mode are available when you touch Controls". It may take a few seconds after inserting the drive. If the Dashcam icon is not there, the car has not accepted the drive and nothing further will help until it does.
Read the Dashcam icon's state. Tesla documents five: Recording (footage is being captured; touch to save), Available (Dashcam is available but not actively recording — touch the icon to start), Paused (touch to resume), Busy (loading, saving or overwriting footage — "while dashcam is busy, footage is not being captured and recorded") and Saved. Note that opening the in-car Viewer pauses Dashcam recording.
Check Controls › Safety › Dashcam is not Off. Auto, Manual or On Honk all keep it enabled for Sentry; Off does not.
Check Controls › Safety › Sentry Mode. Confirm it is on and look at the three Exclude switches. If the event happened at home, at work or at a favourite, an exclusion is the most ordinary explanation for an armed-looking car that did not record.
Check the battery. If it was below 20% at the time, Sentry had switched itself off; the app will have a notification saying so.

The drive itself: Tesla's requirements

If the icons come and go, or the car reports the drive as too slow or asks to format it, measure the drive against the manual's list. A drive that misses any of these will either not be recognised or will drop recordings:

At least 64 GB of storage — and the manual asks for as much available space as possible, because video "can occupy a large amount of space".
A sustained write speed of at least 4 MB/s. Tesla adds that sustained write speed "differs from peak write speed" — the number on the packaging is usually the peak.
USB 2.0 compatible. A USB 3.x drive is fine as long as it also works over USB 2.0.
One of these file systems: exFAT, MS-DOS FAT (FAT32), ext3 or ext4. NTFS is not supported.
A folder named exactly TeslaCam at the root of the drive.

The simplest way to satisfy all of it is to let the car do it: Controls › Safety › Format USB Drive formats the drive as exFAT and creates the TeslaCam folder in one step. The option only appears when a drive with one partition or fewer is in a front port. It erases the drive — so if this drive has ever held footage you might still need, read the formatting guide first and recover before you format. The full step-by-step, including the Mac and Windows routes, is there too.

After formatting, save a test clip: wait for the Dashcam icon, touch it, then confirm on a computer that TeslaCam/SavedClips/ now contains a folder with MP4 files in it. A drive that passes that test is a drive Sentry can write to.

The reverse case: footage with no alert

The separation cuts both ways. The manual notes that if Sentry Mode does not consider an event a clear threat, "the vehicle records footage but doesn't trigger the alarm" — and only sends a phone notification when the alarm is triggered, someone tries a door or trunk, or the car is jolted. With Disable Sentry Sounds on, the alarm is silent but the app is still notified and the last ten minutes of footage are still saved. So a SentryClips folder can hold events you were never told about, and an event you were told about can have no folder. Neither is a malfunction; they are two different triggers.

If the clip was written and is now gone

Everything above is about the car declining to write. The other half of "the event is missing" is the car writing the clip and later removing it: the manual says the oldest Sentry clips are deleted when space runs low, and a format clears the drive's index. In both cases the video data is still physically on the flash until new recording overwrites it, which is the case recovery software exists for. Why Sentry events go missing explains the retention rules; the recovery guide walks through getting the footage back; and how long footage stays recoverable covers the timing.

To be clear about our own scope: ClipSalvage reads the raw sectors of the drive and finds clips the file system no longer lists — deleted, formatted, or encrypted. It cannot produce a clip the car never wrote. The free scan is the quickest way to tell which situation you are in: if clips from around the event turn up, even as deleted entries, recovery applies; if the drive holds nothing from that window at all, the recording never reached it — or has since been overwritten by further driving.

A note on region and software version

Tesla's manual opens its Sentry Mode section with a caveat worth repeating here: depending on market region, vehicle configuration, options purchased and software version, a vehicle "may not be equipped with Sentry Mode or the features may not operate exactly as described". Menu labels and port layouts also vary by model and year. The pages linked below are the Model 3 manual in US English; for your own car, the same sections of your market's manual are the reference, and this article should be read as a map of where to look rather than a promise of what you will find.

Takeaway

"Sentry Mode is on but there is no recording" almost always means the alert fired and the write did not. Check Dashcam is enabled, the drive is in the glovebox port, the Dashcam icon shows Recording, the location is not excluded, and the drive meets Tesla's requirements. If the footage was written and then lost, ClipSalvage can scan for it and recover what it finds; if it was never written, no tool can recover it — and a free scan tells you which.

Sources & references

Tesla owner's manual — Sentry Mode (recording "if installed", no recordings without a drive, Dashcam must be enabled, 20% battery limit, Exclude Home / Work / Favorites, alarm-versus-recording triggers)
Tesla owner's manual — Dashcam (Dashcam icon states, no recording when Off, Viewer pauses recording, port guidance)
Tesla owner's manual — USB Drive Requirements for Recording Videos (capacity, sustained write speed, USB 2.0, file systems, TeslaCam folder, Format USB Drive, recording-capable ports, full-drive and SentryClips deletion behaviour)

Sentry Mode is on but nothing is recording to the USB drive — why?