fault codes 17536 and 17978

[berksboy26]

Hi,
Despite changing 2 off Fwd Lambda sensors - once by a VW specialist and once by myself the engine check light continues to illuminate - displaying fault codes 17536 and 17978.
I don't wish to get into the game of changing every thing until the light goes out - or the bulb fails! - so any help or advise would be appreciated.
The car is a 2001 Mk4 2 LTR GTI with an engine code AJY and shows no signs of running incorrectly.

[martin1810]

Look for an air leak in and around manifold and exhaust.

[phil140]

17536 translates to: Long Term Fuel Trim - System too Lean (Bank 1)
on the list i have, i cannot find a match for 17978.