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Detroit Diesel SPN 3826 FMI 16 indicates that a DPF regeneration cycle was initiated but did not complete successfully. This code appears on DD13, DD15, and DD16 engines and is important to address promptly as repeated incomplete regenerations will allow soot to continue accumulating in the DPF, eventually leading to a soot overload condition and significant derate.
Symptoms
- Check engine light on
- DPF or regen warning light illuminated
- Regen cycle starts but does not finish
- Soot load continuing to rise after attempted regen
- Reduced engine performance
- Engine derate possible if soot continues to accumulate
- May appear alongside DPF soot load codes
Cause
This code triggers when the ECM determines a regeneration cycle did not reach completion within the expected timeframe or conditions. Common causes include:
- Regen inhibit switch activated during regeneration
- Vehicle moved or driven during a parked regeneration attempt
- Exhaust temperatures insufficient to complete soot combustion
- Faulty HC dosing injector not delivering enough fuel during regen
- DPF too heavily loaded to complete regen in one cycle
- Failed DPF temperature sensor affecting regen control Low fuel level preventing regen from completing
- Faulty regen control system interrupting the cycle
Can You Keep Driving?
Limited driving is possible but each incomplete regen allows soot to accumulate further. If the underlying cause is not resolved the DPF will reach critical soot levels triggering a more severe derate. A successful parked regeneration should be completed as soon as possible..
Recommended Action
Attempt another parked regeneration ensuring the vehicle is parked safely, the regen inhibit switch is off, fuel level is adequate, and the vehicle is not moved during the cycle. If the regen fails to complete again have the HC dosing injector, DPF temperature sensors, and regen control system inspected by a qualified diesel technician.
It means a DPF regeneration cycle was started but did not complete successfully, allowing soot to remain in the filter above acceptable levels.
The most common causes are the regen inhibit switch being active, the vehicle being moved during a parked regen, insufficient exhaust temperatures, a faulty HC dosing injector, or a heavily loaded DPF requiring multiple regen attempts.
Short distances may be possible but repeated incomplete regens will cause soot to build to critical levels. A successful parked regeneration should be completed as soon as safely possible.
It can if incomplete regens allow soot to accumulate to critical levels triggering a more severe DPF soot fault and derate condition.
Complete a successful parked regeneration with the inhibit switch off and the vehicle stationary throughout the full cycle. If regen continues to fail have the HC dosing injector and regen control system inspected. The code should clear once a full successful regen is completed.
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.