RET_SMON; Retarder is active while engine torque is higher than a threshold or retarder is active without demand
â–¶ How to fix
Check retarder requests; Check load signal; Check engine torque;
What you'll see
No driver-visible symptom recorded.
System reaction
Switch off retarder;
Diagnostic depth
Detection
Software (Ret_SMON); Normal mode
Possible cause
Retarder is no longer available;