PERFORM THE PROCEDURE OUTLINED IN THIS SERVICE INFORMATION ON ALL AFFECTED VEHICLES BEFORE CUSTOMER DELIVERY OR THE NEXT TIME THEY ARE IN THE SHOP FOR MAINTENANCE OR REPAIRS. SUBJECT Service Action: Replace the SCR Tank. The Service Engine Soon lamp is illuminated. The fault codes stored are related to the SCR active tank temperature sensor. The temperature sensor inside the active tank degrades over time. The sensor is integrated into the SCR (Diesel Exhaust Fluid) tank assembly and is not replaceable separately. AFFECTED VEHICLES This Service Action involves certain E90 vehicles produced from March 2008 to August 2009. First check if a Service Action label with a code number 669 is already attached to the B-pillar. If a code number 669 has been punched out, the Campaign has already been performed and no further action is necessary. Vehicles which require this Service Action to be completed will show it as "Open" when checked either in the "Service Menu" of DCSnet (Dealer Communication System) or with the Key Reader.