Williams also have one remaining mandatory impact test still to pass, on the nose box, although that is not the reason they have decided not to go to Barcelona.
Williams said in a statement that they would instead focus on running the car and engine on a dynamic rig as they prepare for the second pre-season test in Bahrain from 11-13 February.
The other 10 teams are expected to be at the Circuit de Barcelona-Catalunya, where they are permitted to run on a maximum of three of the five days of the test between 26-30 January.
World champions McLaren have already said they will not be ready to run on the first day, and possibly not on the second, because they gave themselves as much time as possible to maximise the design of their new car.
Ferrari are going to run for the first time on Tuesday, while Aston Martin are also not expected to be ready for the first day of the Barcelona test.
Williams, who finished fifth in the constructors’ championship last year, are continuing with Alex Albon and Carlos Sainz as their drivers in 2026.
