High Nox — Possible Fault Codes
Found 1 fault code associated with high nox. Codes are sorted by severity — check STOP ENGINE codes first.
SPN 520605 FMI 7
SCR System Mechanical Malfunction
Detroit Diesel DD15 • Component: SCR Catalyst / NOx Sensors • J1939
⚠️ Diagnostic Note:
Symptoms can have multiple root causes. Always verify with a diagnostic scan tool before replacing parts. The fault codes listed above are possible matches for high nox based on SAE J1939/J1587 fault code definitions and OEM service documentation.