P2BA6 — NOx Exceedance - SCR NOx Catalyst Performance
NOx emissions are above the legal threshold and the ECU isolates the cause to the SCR NOx catalyst. Conversion efficiency is degraded — aged substrate, sulphur poisoning, or thermal damage.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Scr catalyst
- Reductant dosing unit
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- SCR catalyst substrate aged or contaminated
- Thermal damage from prior over-temperature event
Possible symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
- Reduced-power or limp mode may occur
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.