A decade before crash detection shipped free inside every flagship phone, a wave of startups sold small devices that plugged into your car's OBD-II port and promised the same thing: detect a crash, call for help automatically. Some worked. Many did not. The category is worth understanding today, both because its lessons shaped current features and because some of those devices are still in cars.

What plug-in crash detectors were

Every car sold in the United States since 1996 has an OBD-II port - the same diagnostic connector mechanics use to read engine codes. Around 2013-2018, companies sold adapters that plugged into that port and combined three functions:

  • Reading vehicle data: speed, battery voltage, engine alerts
  • Trip tracking and geofencing for parents of teen drivers
  • Crash detection using the adapter's own accelerometer

The pitch was compelling: no monthly phone plan for a separate device, installation in seconds, and automatic emergency notification. Several startups in this space received mainstream tech-press coverage and venture funding during those years.

What worked

  • Vehicle diagnostics. Battery-health alerts and check-engine decoding were genuinely useful and remain the core of today's OBD trackers.
  • Trip logging. Automatic trip records helped families and later fed usage-based insurance programs.
  • The concept itself. Automatic crash notification (ACN) is now standard in phones and connected cars - the idea was right, ahead of its hardware.

What didn't

  • Cellular dependence. Most adapters used 2G or 3G networks. When carriers shut those networks down (2G sunset completed in the US by the early 2020s), thousands of devices went dark permanently.
  • Crash-detection accuracy. An accelerometer in a plastic dongle at the end of a dangling port cable is a noisy sensor. False positives and missed detections were common enough that many products quietly de-emphasized the crash feature.
  • Business model. A $5-10 monthly subscription for features phones would soon give away free was a hard sell once Apple and Google entered.

Where the idea lives on

The function moved into three places: built into phones (iPhone Crash Detection, Pixel Crash Detection), built into vehicles through embedded telematics like OnStar, and folded into modern LTE/4G OBD trackers that focus on fleet and teen-driver monitoring. The underlying physics - sudden deceleration plus impact signature - is unchanged; only the sensor quality and connectivity improved.

If you still have an old plug-in device

Assume its emergency features no longer work unless the manufacturer confirms current-network support. Check whether your phone already covers you for free with built-in crash detection, and see our guide to current GPS trackers for teen drivers if you want vehicle monitoring today.

A note on this site

SplitSecnd is an independent road-safety guide covering the crash detection category as journalists and reviewers. It is not affiliated with any former device manufacturer, and we do not sell hardware.