S2 Legend
Registered User
Hi folks my A4 audi 2.0tdi is showing the glow plug on the dash plugged it into the computer and its coming up with air filter bypass valve that's the problem? It has been having lagging moments which were increasing and this glow plug symbol shows up. I don't have the error code at hand but had it plugged into another computer a more detailed one but it come up with the same diagnosis but a different error code?