Hi everyone, I´ve read here few topics related to this fault codes and I˙m still puzzled with it. I drive Octavia 2017, 1.6 TDI, 225k km. On random I am getting fault, coil sign start to blink sometimes also check engine starts lights up and car goes into limp mode. On diagnostics it`s always P256400 Turbo charger boost control position; sensor circuit: low and P256300 Turbo charger boost control position; sensor circuit: range/performance.

Tested vacuum, tried to change selenoid valve, change connector of actuator because it was a bit damaged. Fault persists, and on random occasion. Sometimes it`s on already on car startup sometimes during drive and sometimes it droves perfectly. Car was few days with my mechanic and he could not replicate fault, car was going perfect for few days and all parameters was good. He than made regeneration of DPF. Of course that did not change anything after a day fault was there again. Coil blinks, sometimes check engine, always limp mode.

Has anyone idea what could i do? I`m thinking of replacing all vacuum tubes just to be sure and maybe cleaning of turbo.

BTw A year and a half ago the fault was on and I replaced actuator, the fault persisted and after mechanic cleaned some connectors fault was gone, and drove for year and a half wit no errors.

The turbo actuator has issues on both TSI and TSI engines. Its usually caused by the actuator mechanism sticking. This sticking is caused by lack of use. One thing that VAG engines do not like is being driven gently. Drive it like its stolen....or at least lots of progressive acceleration. Make sure you can manually open/close the actuator that it is at least moving correctly.

Officially, fill up the car with some super diesel and run several tanks of that through the car. Its not an DPF problem (unless the car has not been allowed to regen); but I would recommend the super diesel to help clean out the EGR and DPF. You've got the drive the car hard (make sure fluids are all topped off and tyres are good before going for it). You want that turbo actuator to work, lots of opening/closing and spooling of the turbo.

My solution is unauthodox, but it works for me. I tend to buy normal diesel and put in some https://www.hydra-int.com/DPB000K.html DPB100 in with each tank - which helps the burn process and helps keep DPF, EGR and injectors clean. Others would say its not necessary, but I've owned several TDI's and they have all responded well to this solution.

Agree with exercising the turbo actuator, reasonably sure that too gentle driving contributed to SHMBOs Fabia recent failure.

She revs it out a fair bit more through the gears now.