Powertrain
generic / SAE
P20EE
NOx Catalyst Efficiency Below Threshold (Bank 1)
The SCR catalyst on bank 1 is no longer reducing NOx to the level the ECU expects, even with proper reductant dosing and quality. Often the result of catalyst poisoning by sulphur or hydrocarbons, thermal aging, or a leak between the upstream and downstream NOx sensors.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / EE
Possible causes
- SCR catalyst aged or poisoned high
- NOx sensor drift medium
- Exhaust leak between upstream and downstream NOx sensors low
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 400–3500 €
- Estimated time: 1.5–6 h
- Component: scr catalyst
- Component: nox sensor upstream
- Component: nox sensor downstream
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012