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Top Tip - VAG

Engine warning light due to carbon deposit build up on the throttle valve

Covers -  Most 2.0 Common Rail Diesel from 2011 onwards


The engine warning light is on, on the instrument panel cluster.

Fault codes

  • P2112
  • P0121
  • P2111 (throttle/valve).


Carbon deposits build up on the throttle valve, due to incorrect fitting of the Exhaust Gas Recirculation (EGR) pipe from the factory.








  1. Remove the throttle body, clean off all carbon deposits and refit.
  2. Remove the EGR pipe from the side of the manifold.
  3. Remove the EGR insert on manifold (2 x Torx screws). Turn 180 degrees (pictured right), making sure the exhaust gases are directed towards the engine and not the throttle valve. (A small round file may be required to modify the insert to fit to the manifold).
  4. Refit everything and road test the car.
  5. If the throttle body codes returns, then a replacement part is required.