Troubleshooting steps
Check emission components
Manufacturer DTCs
Mercedes B3021 – DME: Emission control fault
Emission control fault
Details
Mercedes B3021 error indicates emission control fault. Catalyst issue, EGR problem.
Error typeemission
MeaningEmission control fault
Typical causesCatalyst issue, EGR problem
SolutionsCheck emission components
SeverityMedium
Catalog references
Where this appears
Mercedes-BenzB3021
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What does B3021 mean on Mercedes?
B3021 on Mercedes indicates emission control fault.
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