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Detroit Diesel SPN 3556 FMI 16 indicates a fault with the hydrocarbon dosing injector, which is the component responsible for injecting fuel into the exhaust stream to raise temperatures during active DPF regeneration. When this injector fails on DD13, DD15, and DD16 engines the aftertreatment system cannot generate the heat needed to burn off soot and active regeneration cycles will fail to complete.
Symptoms
- Check engine light on
- DPF or regen warning light illuminated
- Active regeneration unable to complete
- DPF soot load continuing to rise
- Engine derate possible as soot accumulates
- May appear alongside incomplete regen or soot load codes
Cause
This code triggers when the ECM detects the hydrocarbon dosing injector is not performing within specification during a regeneration cycle. Common causes include:
- Clogged or carbon fouled HC dosing injector
- Failed HC dosing injector solenoid
- HC dosing injector stuck open or closed
- Fuel supply issue to the dosing injector
- Damaged or corroded injector wiring or connector
- HC dosing pump failure reducing fuel pressure to injector
- Water or contamination in the HC dosing fuel supply
Can You Keep Driving?
Limited driving is possible but without a functioning HC dosing injector active regeneration cannot be completed. 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
Have the HC dosing injector inspected for carbon fouling or physical damage. Check the injector wiring and connector for corrosion or damage. Test fuel supply pressure to the injector and inspect the HC dosing pump if pressure is low. A clogged injector may be cleanable but replacement is often the most reliable solution.
It means the hydrocarbon dosing injector that supplies fuel to the exhaust for DPF regeneration is not functioning correctly, preventing active regeneration cycles from completing.
The most common causes are a clogged or carbon fouled HC dosing injector, a failed injector solenoid, damaged wiring, or a fuel supply problem to the injector.
Short distances may be possible but without active regeneration capability soot will accumulate in the DPF leading to more severe faults and derate conditions.
Not immediately but as soot accumulates due to failed regeneration cycles more severe DPF soot codes will trigger derate conditions.
Inspect clean or replace the HC dosing injector and verify fuel supply and wiring. Once the injector is functioning correctly and a successful active regeneration is completed 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.