Causes
- A GPS cold start that hasn't finished its satellite search yet — the Omni's built-in GPS has to acquire and lock onto satellites before it can stamp speed and coordinates on the recording. 70mai's official Omni FAQ states plainly that a watermark showing all "- -" means "the GPS search and positioning is not yet successful, please wait patiently" — it is the single most common reason for the dash cam's location data being blank right after installation or a long period powered off.
- A metal film (metallic-tinted windshield) blocking the GPS signal — 70mai's FAQ warns explicitly: "If the metal film is attached to the front windshield, it will block the GPS signal to the vehicle cabin." Heat-reflective coatings containing metal act as a Faraday cage for the GPS radio, so the camera's antenna never sees satellites no matter how long you wait — a permanent "- -" watermark is the signature.
- Driving through GPS dead zones — tunnels, underground garages, dense high-rise canyons — when the vehicle is in a location without satellite visibility, the watermark reverts to "- -" for the duration. 70mai's FAQ confirms the app cannot refresh the vehicle's location while the car passes through tunnels or areas without coverage, since the feature "can only wait for the vehicle to reach an area where there is 4G network signal and satellite positioning signal coverage."
- The wrong parking location shown after the vehicle shuts off — once the car is parked, the Omni turns the satellite positioning module off to save power, reports its parking location, and can only display "the last location successfully positioned before the vehicle shuts off." If the car sits in an underground garage or indoor lot with no 4G or satellite signal, the app shows the last reported position from the trip — which can look like a GPS error when it is actually a power-saving design limit.
- No 4G kit installed, so A-GPS assistance is unavailable — the Omni automatically turns on A-GPS (assisted positioning using network data) when the 4G parking surveillance cable is connected and enabled, which "greatly improves the speed and accuracy of GPS star search and positioning." Without the 4G kit, cold fixes can take noticeably longer, making the "- -" watermark linger.
How to Fix
- Give the cold start time — drive for a few minutes in open sky — after installing the camera or after it has been powered off for days, the first satellite fix can take several minutes. Drive on an open road away from tall buildings and watch the watermark; once the GPS locks, speed and coordinates populate and stay populated. This is the first step 70mai's own FAQ points to.
- Check for a metallic windshield film — if the watermark stays "- -" for the whole drive in open sky, the front windshield may have a metal-coated film. 70mai's FAQ names metal film as a direct cause of blocked GPS. Move the camera temporarily to a side window or test it in a vehicle without the film to confirm; if the film is the culprit, you will need to keep the camera at a non-filmed window position or a GPS repeater designed for metallic windshields.
- Power-cycle the dash cam to restart the GPS receiver — unplug the USB power cable from the camera body and plug it back in, or long-press the power button to shut it down and press it again to boot. A fresh boot forces the GPS module to re-run its cold-start search, which clears a stuck searching state.
- Update the camera firmware and the app — in the 70mai app, connect to the camera's Wi-Fi, open device settings → firmware update, and install any pending build. GPS acquisition logic and location reporting have been refined in Omni firmware updates, and the app-side maps depend on matching versions.
- Fit the 4G parking surveillance kit to enable A-GPS — if you regularly park underground or want faster fixes, install the 70mai 4G hardwire kit and enable its 4G networking. Per the Omni FAQ, this automatically activates A-GPS, "greatly improving the speed and accuracy of GPS star search and positioning," and it is also what makes the parking location reportable in the first place after shutdown.
- Read the "parking location" with the power-saving design in mind — after the car is shut off in a garage or indoor lot, the app can only show the last location fixed before shutdown, because the dash cam powers down its satellite receiver to save battery. Don't treat this as a fault: drive the car into open sky once and confirm the location updates — and remember the camera reports its position roughly every 3 minutes while driving, so a very fresh "last location" requires several minutes of driving before parking.
- Contact 70mai support if speed/coordinates never appear anywhere — if the watermark remains "- -" in open sky, without metal film, after power cycles and firmware updates, the GPS receiver or antenna may be faulty. Contact 70mai support with your order number, a short clip of the persistent "- -" watermark from a drive in open sky, and confirmation of your windshield type — owners with hardware faults were walked through checks and offered replacement units.