An electric throttle valve assembly primarily consists of the following parts: throttle valve body, solenoid drive, potentiometer, controller (or ECU in place of controller), and bypass valve. The valve may experience two types of failure: hard and soft failure. Hard failure refers to mechanical damage, while soft failure refers to contamination or misalignment.
Hard failure
The resistance part of the potentiometer is produced by spraying a carbon film coating on the PET base. This is actually a very elementary manufacturing process that results in low wear strength. In fact, such device is even inferior to potentiometers used in home appliances. Its sliding contact is formed by a row of reverse claws made of stainless steel. The reverse claw structure makes things worse! Moreover, due to absence of protective agent on the carbon film, chipped carbon powder may cause ill contact and naturally trigger the visual fault alarm. There was a case in which the carbon film was badly scratched after only 70 thousand km of mileage. The driver operated rather carelessly!
Soft failure
Cleaning of a throttle valve is often a challenging task, because it is open with a very small angle most of the time. As air flows rapidly (several dozen to several hundred meters per second)through the gap of the throttle valve, the gradually accumulated dirt may interfere with the air flow to an extent beyond adjustability of the throttle valve.

Name: throttle valve
Ref No. : 03C128063A
Product system: electrical device
Brand: vika
Applicable models:
Skoda: FAB11-15
VW: BE12-16/BEC13-16/CC12-17/EOS09-16/GOC12-16/GOLF07-14/GOPL08-14/JE06-14/PA09-15/PACC09-12/PO10-14/SCI09-14/SHA11-16/TIG08-18/TOU06-15
Seat: A1 11-14
Audi: AL11-15/IB09-12