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Detroit Diesel SPN 3697 FMI 16 indicates that the fuel pressure supplying the aftertreatment hydrocarbon dosing system is below the required threshold. This code appears on DD13, DD15, and DD16 engines and means the HC dosing system cannot deliver adequate fuel to the exhaust stream during active regeneration, preventing the DPF from reaching the temperatures needed to burn off accumulated soot.
Symptoms
- Check engine light on
- DPF or regen warning light illuminated
- Active regeneration unable to complete
- DPF soot load rising due to failed regens
- Engine derate possible as soot accumulates
- May appear alongside HC dosing injector or incomplete regen codes
Cause
This code triggers when the aftertreatment fuel pressure sensor detects pressure below the minimum required threshold for HC dosing during regeneration. Common causes include:
- Failing or worn HC dosing fuel pump
- Clogged aftertreatment fuel filter
- Fuel supply line leak or restriction
- Low main fuel tank level affecting supply pressure
- Faulty aftertreatment fuel pressure sensor
- Air in the HC dosing fuel supply lines
- Clogged HC dosing injector creating back pressure issues
Can You Keep Driving?
Limited driving is possible but without adequate fuel pressure the HC dosing system cannot support active regeneration. Soot will continue to accumulate in the DPF leading to progressively more severe fault codes and derate conditions. Address this fault before soot reaches critical levels.
Recommended Action
Check main fuel tank level first as low fuel can affect HC dosing supply pressure. Inspect the aftertreatment fuel filter and replace if clogged. Check fuel supply lines to the dosing system for leaks or restrictions. If filter and lines are good have the HC dosing pump tested and replaced if not generating adequate pressure.
It means the fuel pressure supplying the hydrocarbon dosing system is below the required threshold, preventing the system from delivering adequate fuel to the exhaust for active DPF regeneration.
The most common causes are a failing HC dosing pump, a clogged aftertreatment fuel filter, a fuel supply line restriction or leak, low fuel tank level, or a faulty fuel pressure sensor.
Short distances may be possible but without adequate HC dosing fuel pressure active regeneration cannot complete and soot will accumulate leading to more severe DPF faults and derate.
Not immediately but as soot accumulates from failed regeneration cycles more severe DPF soot codes will trigger derate conditions.
Check fuel level and replace the aftertreatment fuel filter. If pressure remains low inspect the HC dosing pump and fuel supply lines. Once adequate fuel pressure is restored and a successful active regeneration completes the code should clear.
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.