AI DamageShort answer
Many modern cars have a pyrotechnic fuse that cuts power in a crash to prevent a short circuit and fire. It is single-use. Once it has fired, the car may not start even after a small impact, and at auction it sells as Stationary.
What the part is
A pyrofuse (pyrotechnic battery disconnect) is a small charge in the battery cable or inside a high-voltage battery. The airbag control unit fires it at the moment of impact and the cable is physically cut. This stops the power cable from shorting against a damaged body after the crash.
In conventional cars the pyrofuse usually sits on the positive battery cable, especially when the battery is in the boot. In electric and hybrid cars a separate pyro element disconnects the high-voltage battery.
What a fired pyrofuse looks like
| What the buyer sees | What it may actually be |
|---|---|
| The car is “dead” and does not react to the key | The pyrofuse fired although the battery is charged |
| The dashboard lights up but the starter does not turn | The power circuit is cut while the low-current circuit is alive |
| An EV will not switch to Ready | The high-voltage battery was disconnected by the pyro element |
| SRS fault after a light hit | The airbag unit recorded an event and may have fired the pyrofuse |
What it means for the lot
- Stationary does not mean the engine is dead. Nor does it prove the pyrofuse is the only cause. Without diagnostics it is unknown.
- A pyrofuse is not reset or repaired. It is replaced together with the cable or module.
- After firing, the airbag unit stores the event. It must be checked and often replaced or reprogrammed (see airbags and SRS).
- On an EV, replacing the battery pyro element is high-voltage work. Only a certified shop should do it (see EV after a crash).
How to check before and after purchase
- In the photos, look for deployed airbags and a damaged cable near the battery if it is visible.
- Find out where the battery sits on this model and whether it has a pyrofuse. The manufacturer’s service documentation shows this.
- After purchase, read the fault codes first and only then replace the battery or starter.
- Do not jump the car around a cut cable. That bypasses the protection the pyrofuse exists for.
What start statuses on a lot page mean: Run and Drive and Engine Start.