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Detroit Diesel SPN 3720 FMI 16 indicates that the calculated soot load percentage inside the Diesel Particulate Filter has exceeded the acceptable threshold. This code appears on DD13, DD15, and DD16 engines and represents the ECM’s percentage based calculation of DPF soot loading. When this percentage rises above acceptable limits regeneration is required to prevent derate conditions and potential DPF damage.
Symptoms
- Check engine light on
- DPF or regen warning light illuminated
- Regeneration request active Reduced engine performance
- Engine derate possible if soot percentage continues to rise
- May appear alongside DPF differential pressure codes
Cause
This code triggers when the ECM calculates the DPF soot load percentage has risen above the acceptable threshold based on differential pressure readings and engine operating data. Common causes include:
- Frequent short trips preventing passive regeneration
- Excessive idling not allowing exhaust temperatures to reach regen levels
- Failed or incomplete active regeneration cycles
- Faulty DPF differential pressure sensor affecting soot calculations
- Engine running rich causing accelerated soot production
- Regen inhibit switch preventing regeneration cycles
- Partially clogged DPF reducing regen effectiveness
Can You Keep Driving?
Limited driving is possible but soot load percentage will continue to rise without a successful regeneration. A parked regeneration should be performed as soon as safely possible to prevent escalation to a more severe derate condition.
Recommended Action
Perform a parked regeneration as soon as possible ensuring the inhibit switch is off and fuel level is adequate. If the regen completes successfully and the code clears monitor for recurrence. If soot load percentage continues to rise after successful regens have the DPF differential pressure sensor, engine fueling system, and DPF condition inspected.
It means the ECM has calculated that the percentage of soot accumulated inside the DPF has exceeded the acceptable threshold and regeneration is required to prevent further escalation.
The most common causes are frequent short trips, excessive idling, failed regeneration cycles, a faulty differential pressure sensor, or engine conditions causing excessive soot production.
Short distances are possible but a parked regeneration should be performed as soon as safely possible to reduce soot load percentage before more severe codes and derate conditions develop.
Yes if soot load percentage continues to rise without a successful regeneration the ECM will trigger progressive derate conditions to protect the DPF.
Perform a successful parked regeneration to reduce soot load percentage. The code should clear once the ECM calculates soot has dropped below the threshold. If it returns frequently investigate the underlying cause of excessive soot accumulation.
Related codes
Need Immediate Help With This Fault Code?
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Important Notice
The information provided above is for general informational purposes only and should not replace official OEM service procedures. Always consult the manufacturer’s service manual or a qualified diesel technician before performing repairs. Operating a vehicle with active fault codes may result in further damage.