What usually causes P0173?

Intake leak, MAF, fuel pressure, injectors.

P0173Fuel trim (bank 2)

P0173 means “Fuel trim (bank 2)”. It's a generic powertrain code (fuel and air metering), so it means the same on every make, including VW, Škoda, Audi, SEAT and Cupra.

Fix soon
SystemFuel mixture
TypeGeneric (same on all makes)
VCDS number16557

How urgent is it?

Worth fixing soon; usually drivable meanwhile, but watch for symptoms.

Which system and module

Scanline files it under Fuel mixture. The first letter, P, means powertrain (engine, transmission, emissions).

Usually stored by the engine control unit (VCDS address 01, Engine).

What usually causes it

Intake leak
MAF
fuel pressure
injectors

Typical causes are a starting point, not a diagnosis of your car.

Related codes

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Scanline explains fault codes; it isn't a repair authority. This page explains what the code means; it can't tell you what is wrong with your car. Ross-Tech's wiki has their own notes on VW Group faults.