What usually causes P20EE?

Poor AdBlue quality, dosing valve, NOx sensor, SCR catalyst.

P20EESCR NOx catalyst efficiency below threshold (bank 1)

P20EE means “SCR NOx catalyst efficiency below threshold (bank 1)”. It's a generic powertrain code (fuel, air metering and emission controls), so it means the same on every make, including VW, Škoda, Audi, SEAT and Cupra.

Fix soon
SystemEmissions
TypeGeneric (same on all makes)

How urgent is it?

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

Which system and module

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

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

What usually causes it

Poor AdBlue quality
dosing valve
NOx sensor
SCR catalyst

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.