90 23 Fuel level display:

Only 911 Carrera 4 (996) and GT3 are affected: 

If the power supply is interrupted by a discharged or disconnected battery with the tank containing less than 19 I, the calculated value for the range on remaining fuel in the instrument cluster will be incorrect or deleted.

If the tank contains less than 10 I, it is possible that the fuel level warning light is no longer activated.

1. If the power supply is restored with the fuel level at less than 19 I, it is possible that the fuel level display may subsequently display too much in some 996 Carrera 4 and GT3 vehicles.

This may lead to the vehicle breaking down. 

Remedy in these vehicles: 

Refill at least 19 I of fuel; then the fuel level sensor is in operating range and its display precision is guaranteed.