Toro Rosso may have to sit out the 2017 finale in Abu Dhabi.
Germany's Auto Motor und Sports reports that as the second Red Bull team hit regular problems with their Renault-supplied MGU-H unit, the French manufacturer is almost out of spare parts.
"Toro Rosso looks like a spare parts store for vintage cars," said Red Bull official Dr Helmut Marko.
Renault boss Cyril Abiteboul confirmed that the spare parts situation with regards to Toro Rosso is at a critical point.
"These components have such a long lead time. They cannot be built in two weeks."
Toro Rosso are sixth in the team standings with two races of 2017 remaining.