I just serviced an Audi A3 2004 model and it keeps on giving me this code P0171 (system to lean : bank 1)...

What could cause this that would be connected to the service since it didn't do it before...

I changed spark plugs, fuel filter, oil and oil filter...

Whenever I delete it it just comes up again...

Thanks for any help...

 

Vacum hose broken somewhere

You very well could have broke it during the service

 

That's what I suspected so I had a quick check but found nothing...

What else could cause this????