The Tesla Model S is getting a new titanium underbody shield after two fires caused by road debris striking the underside of the cars have been reported. The fix follows an over-the-air software update released a few months ago that raises the ride height at highway speeds.

The shield consists of three parts – a rounded, hollow aluminium bar, a titanium plate and a shallow angle solid aluminium extrusion. These are designed to deflect or crush errant objects away from the battery pack and other sensitive components, or if the objects are incompressible and immovable, force the Model S up and over them.

Tesla claims that the shields “bring this risk down to virtually zero”, having tested them 152 times over a variety of scenarios without causing any damage that could cause a fire. These include driving over hardened steel structures, equivalent to running into a steel spear set into the tarmac.

The shields are claimed to cause only a 0.1% reduction in range, with no discernible changes to the ride, handling or aerodynamics. All Tesla Model Ss built after March 6 have been fitted with the new shields, and current owners will have them retrofitted free-of-charge, either by request or during their next service.