P20EE fault code: what it means

P20EE: Diesel SCR (AdBlue) NOx catalyst is not reducing NOx enough. Can lead to a countdown to limp mode or no-restart.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

poor-quality or old AdBlue
AdBlue injector blocked with crystals
faulty NOx sensor
worn SCR catalyst

P20EE by make

Audi

AdBlue (SCR) system not cutting NOx enough. On VW group diesels the catalyst itself is rarely the fault; check the AdBlue fluid, dosing and NOx sensors.

Usual causes: old, contaminated or wrong-strength AdBlue; AdBlue dosing fault (crystallised injector, pump, valve); faulty NOx sensor; worn SCR catalyst (least likely)

BMW

SCR (AdBlue) NOx catalyst efficiency low, bank 1. Common on newer BMW diesels; may limit restarts if left.

Usual causes: NOx sensor reading wrong; AdBlue quality or dosing fault; worn SCR catalyst

Ford

SCR (AdBlue) catalyst efficiency too low: NOx is not being cleaned enough. Seen on 2019-on Ranger and Everest 2.0 bi-turbo with AdBlue.

Usual causes: faulty downstream NOx sensor; AdBlue dosing pump or injector problem; poor quality or wrong AdBlue; worn SCR catalyst (least likely)

Jeep

SCR (AdBlue/DEF) NOx catalyst efficiency below threshold on 3.0 EcoDiesel.

Usual causes: NOx sensor; poor quality AdBlue; dosing injector; aged SCR catalyst

Land Rover

SCR (AdBlue) NOx catalyst efficiency below threshold on later SDV6/Ingenium diesels with AdBlue.

Usual causes: poor quality or crystallised AdBlue; faulty NOx sensor; AdBlue dosing injector fault; aged SCR catalyst

Mercedes-Benz

SCR (AdBlue) catalyst NOx efficiency below threshold. Mercedes BlueTEC may start a countdown to no-start.

Usual causes: faulty NOx sensor; poor-quality or crystallised AdBlue; clogged or faulty AdBlue dosing valve; exhaust leak

Skoda

AdBlue (SCR) system not cutting NOx enough. On VW group diesels the catalyst itself is rarely the fault; check the AdBlue fluid, dosing and NOx sensors.

Usual causes: old, contaminated or wrong-strength AdBlue; AdBlue dosing fault (crystallised injector, pump, valve); faulty NOx sensor; worn SCR catalyst (least likely)

Volkswagen

AdBlue (SCR) system not cutting NOx enough. On VW group diesels the catalyst itself is rarely the fault; check the AdBlue fluid, dosing and NOx sensors.

Usual causes: old, contaminated or wrong-strength AdBlue; AdBlue dosing fault (crystallised injector, pump, valve); faulty NOx sensor; worn SCR catalyst (least likely)

What the repair usually costs

Automatic transmission rebuild, 6-speed and up (sent to specialist)NZ$7,190–NZ$13,080 · A$6,190–A$11,830
DSG / dual-clutch mechatronic unit replacement (new or reman)NZ$4,300–NZ$7,160 · A$3,750–A$6,390
DSG mechatronic repair / rebuild (unit sent to specialist)NZ$2,070–NZ$4,800 · A$1,890–A$4,250
Electronic throttle body replaceNZ$470–NZ$1,290 · A$440–A$1,190

Not sure what P20EE means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.