0F0309 Mercedes Fault Code :
Read the description of 0F0309 in TCM01B and the engine lights up for TCM01B - TCMV Transmission Control Module Voith code, there are some possible causes for it.
CAN - Protokoll VOITH private CAN Timeout der CAN-Empfangsbotschaft PRV_WPC_0x18FF0320 (Actual Values Water Pump (WPC)).