I have tried spraying water in the enginebay, starter gas and also scotty kilmers smoke test. Learn what system too lean bank 1 means, location and how to repair. If it is one cylinder, try moving the plugs and coils to a different cylinder to see if the problem moves
New 2023 Volkswagen Passat: engines, technology and details - pictures
If it doesn't move with the parts, i'd be onto a compression test for that cylinder.
Modern volkswagen and audi gasoline engines use advanced onboard diagnostics (obd) to monitor engine performance, including the detection of misfires
Misfires are identified by measuring subtle. I don't know if your engine has the coils sitting on the plugs or not like my dead audi allroad sitting in the yard does, but my v6 vw passat has old fashioned plug wires running from. Faulty spark plugs can hinder proper ignition, while damaged ignition coils fail to deliver adequate voltage to the spark plugs I always recommend inspecting the ignition components for.
P0171 indicates that your volkswagen passat is either getting too much air or not enough fuel A clogged or damaged fuel injector will cause the air. Repair information for p0171 volkswagen code