Trouble Code Decoder
Decode J1939-73 DM1 and DM2 diagnostic messages into lamp status and individual trouble codes — SPN, FMI, conversion method and occurrence count — with names resolved against the full SPN dictionary. Paste raw payload bytes, or drop in a whole candump trace and let the tool find and reassemble the multipacket DM1s for you.
Presets:
Paste a DM1 or DM2 payload — or an entire CAN trace — to decode its diagnostic trouble codes.
Technical Legend
DM1 Active Diagnostic Trouble Codes (PGN 65226)
DM2 Previously Active DTCs (PGN 65227)
SPN Suspect Parameter Number (19 bits)
FMI Failure Mode Identifier (5 bits)
CM SPN Conversion Method (1 bit)
OC Occurrence Count (7 bits)
MIL Malfunction Indicator Lamp
BAM Broadcast Announce Message (multipacket)