🟡 Mercedes E220 CDI OM651 DPF blocked — regeneration failure

DPF warning light with reduced engine power. The OM651 diesel particulate filter blocks prematurely on vehicles used predominantly in urban conditions. The engine management system attempts forced regeneration but the exhaust temperatures required cannot be reached in slow traffic. A professional forced regeneration using diagnostic equipment clears the filter. Fitting a DPF cleaning additive to the fuel tank before the next motorway run helps maintain filter cleanliness.