Detailed guide for SPN 5246 FMI 16
Back to top ↑SPN 5246 FMI 16 - SCR Operator Inducement (Moderate Severity)
**What This Means**: This is the intermediate stage of inducement. The ECM has already counted down through FMI 15 and is now enforcing a more severe derate - typically 50-60% power reduction [citation:2].
**Real Driver Story**:
*"My 2020 London Aire with Cummins showed 5246 FMI 16 and audible alarm. Spartan told me it would be OK to drive unless real cold weather. They were wrong - within a week it progressed to FMI 0 and 5 mph derate. Had to be towed to Cummins. Found the DEF head sensor was bad."* — iRV2 forum user [citation:2]
🔧 Why This Happens
The ECM follows EPA-mandated "progressive inducement algorithms" [citation:2]:
1. **FMI 15** - First stage (25% derate) - ignored for period of time
2. **FMI 16** - Second stage (50-60% derate) - you are HERE
3. **FMI 0** - Final stage (5 mph) - next stop
⚠️ Critical Warning
If you have FMI 16, **you are very close to being parked**. The next time you shut down and restart, you may find FMI 0 and 5 mph limit [citation:2].
**Do NOT drive this truck without fixing the root cause.** Get a mobile Cummins/Detroit/Volvo tech to you immediately.
Mechanic community notes for SPN 5246 FMI 16
Back to top ↑Real-world tips from technicians. Submissions are moderated to keep spam and “my cousin fixed it with duct tape” content out.
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