Abstract. The Runtime Verification ECU (RV-ECU) is a new development platform for checking and enforcing the safety of automotive bus communications and software systems. RV-ECU uses runtime verification, a formal analysis subfield geared at validating and verifying systems as they run, to ensure that all manufacturer and third-party safety specifications are complied with during the operation of the vehicle. By compiling formal safety properties into code using a certifying compiler, the RV-ECU executes only provably correct code that checks for safety violations as the system runs. RV-ECU can also recover from violations of these properties, either by itself in simple cases or together with safe message-sending libraries implementable on third-party control units on the bus. RV-ECU can be updated with new specifications after a vehicle is released, enhancing the safety of vehicles that have already been sold and deployed. Currently a prototype, RV-ECU is meant to eventually be deployed as global and local ECU safety monitors, ultimately responsible for the safety of the entire vehicle system. We describe its overall architecture and implementation, and demonstrate monitoring of safety specifications on the CAN bus. We use past automotive recalls as case studies to demonstrate the potential of updating the RV-ECU as a cost effective and practical alternative to software recalls, while requiring the development of rigorous, formal safety specifications easily sharable across manufacturers, OEMs, regulatory agencies and even car owners.