SCR system and AdBlue
P20EE and P2BAD: SCR efficiency and NOx levels
P20EE assesses SCR catalyst efficiency for bank 1. P2BAD reports an exceeded NOx level. Both concern the outcome of exhaust aftertreatment, but assess different things.
At a glance
What the codes tell you
- P20EE
- SCR catalyst efficiency below threshold (bank 1).
- P2BAD
- NOx level exceeded.
How the entries differ
- P20EE is an SCR catalyst efficiency assessment for bank 1.
- P2BAD reports an exceeded NOx level.
- Efficiency, measured NOx level and the underlying cause are not the same thing.
What is not yet established
- P20EE does not prove that the catalyst or a NOx sensor has failed.
- P2BAD does not identify the cause of the assessed NOx level.
- The code describes the control unit’s assessment. It determines neither which component needs replacing nor the repair required.
- Manufacturer-specific descriptions, status, freeze-frame data and live readings can materially change the interpretation.
Diagnostic information that helps next
A reliable assessment does not consider the code in isolation. The following information turns a number into a fault condition that can be investigated:
- NOx readings and sensor positions upstream and downstream of the catalyst
- Exhaust temperatures and operating conditions when the fault occurred
- Dosing request, reductant pressure and relevant accompanying codes
- Exhaust layout, repair history and vehicle software version
More codes for this system
- P202A, P203A, P203B, P203C, P203D, P203E, P203F, P205BP202A, P203A–P203F and P205B: AdBlue tank and levelSCR system and AdBlue
- P2047, P208A, P208B, P20E8, P20E9P2047, P208A/P208B and P20E8/P20E9: AdBlue pressureSCR system and AdBlue
- P204F, P207FP204F and P207F: AdBlue system performance and qualitySCR system and AdBlue
Frequently asked questions about P20EE, P2BAD
What do fault codes P20EE, P2BAD mean?
P20EE: SCR catalyst efficiency below threshold (bank 1). P2BAD: NOx level exceeded.
Which component needs replacing for P20EE?
The code does not determine that. The full diagnostic description, fault status, freeze-frame data, live readings and vehicle-specific system checks determine the appropriate repair.
What information helps with diagnosis?
Useful information includes NOx readings and sensor positions upstream and downstream of the catalyst, Exhaust temperatures and operating conditions when the fault occurred, Dosing request, reductant pressure and relevant accompanying codes, Exhaust layout, repair history and vehicle software version.
Traceable sources
Sources and scope
The descriptions are our own factual explanations of standardised generic OBD definitions. Manufacturer-specific P1xxx codes and differing manufacturer descriptions are not given blanket interpretations here.