Why They Normally Fail The Audi A4 1.9TDi and Audi A4 2.0TDi, both being Diesel Particulate Filter (DPF) models commonly suffer problems with the turbo charger unit failing. Other common problems for the Audi A4 1.9 & 2.0 TDi (DPF model) is Diesel Injectors failing & Engine Oil…