Door Lock Failure in Xiaomi SU7 Crash

The door wouldn’t open after the Chengdu crash—a low-voltage fault sealed the driver’s fate.

Final investigation results released by Sichuan Xihua Traffic Judicial Appraisal Center detail a fatal Oct 13, 2025 crash involving a Xiaomi SU7 Ultra. The car was racing at 167 km/h at impact, well above the 80 km/h limit, with the driver suspected of drunk driving. After colliding with another vehicle, it crossed the median and caught fire, killing the driver. The pivotal finding: doors could not open from the outside because the low-voltage system failed after the collision, disabling electronic door handles. The high-voltage battery had short-circuited on impact, sending abnormal current into the low-voltage circuit. The vehicle relies on electronic release buttons and has no external mechanical emergency handles. In short, death was attributable to burns rather than blunt-force injuries.

Legal-appointed reviewers stress the structural failure of a modern EV’s safety redundancy: when the primary egress is electronic, a collision-induced LV fault can render it inoperable just as occupants need a way out. The report’s nuance—electronic door releases with no mechanical fallback—has immediate implications for how carmakers balance convenience and safety on the factory floor and the showroom.

For Xiaomi, a tech group with expanding automotive ambitions, the incident lays bare a broader industry dynamic: the integration of high- and low-voltage systems in China’s EV supply chain is not just a matter of efficiency but of survivability under extreme crashes. The SU7’s architecture links high-voltage battery behavior to low-voltage control networks, a configuration increasingly common as automakers push compact, software-driven interiors. The finding that a low-voltage fault could disable exterior door operations underscores a design trade-off: fewer mechanical redundancies may improve packaging and cost, but they also raise the stakes for egress reliability in severe accidents.

From a policy and market vantage point, the case spotlights two persistent themes in China’s auto ecosystem. First, the country’s rapid shift to EVs has intensified reliance on domestic suppliers for both HV and LV components, with China’s regulators emphasizing crash safety, electronic controls, and long-term fault tolerance. Second, when an incident ties electronic control failures to life-critical functions, it invites closer scrutiny of engineering standards and testing regimes—something Beijing’s policy push toward safety-oriented quality controls tends to accelerate, even as it complicates supply chains and product cycles.

Industry observers will be watching five levers next:

In the end, the SU7 crash isn’t just a grim tragedy; it’s a case study in the evolving DNA of China’s manufacturing ecosystem: sophisticated electronics, aggressive cost-downs, and the stubborn, stubborn fact that safety choices on the assembly line often translate into real-world consequences behind the wheel.