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Detroit Diesel SPN 3698 FMI 16 indicates that the fuel pressure supplying the aftertreatment hydrocarbon dosing system has exceeded the acceptable operating threshold. This code appears on DD13, DD15, and DD16 engines and signals a problem within the HC dosing fuel supply system that can affect regeneration control and potentially damage dosing system components if not addressed.
Symptoms
- Check engine light on
- DPF or regen warning light illuminated
- Active regeneration may be affected
- HC dosing system operating abnormally
- Possible fuel leaks from pressurized dosing components
- May appear alongside HC dosing injector codes
Cause
This code triggers when the aftertreatment fuel pressure sensor detects pressure above the maximum acceptable threshold in the HC dosing system. Common causes include:
- Faulty HC dosing fuel pressure regulator stuck closed
- Blocked or restricted HC dosing fuel return line
- Failing HC dosing pump delivering excessive pressure
- Clogged HC dosing injector creating pressure buildup
- Faulty aftertreatment fuel pressure sensor giving false high readings
- Kinked or pinched fuel return line restricting flow back to tank
Can You Keep Driving?
Limited driving may be possible but excessive pressure in the HC dosing system can damage fuel lines, fittings, and the dosing injector. Address this fault promptly to avoid more costly repairs to the aftertreatment system.
Recommended Action
Inspect the HC dosing fuel return line for kinks, blockages, or restrictions. Check the fuel pressure regulator for proper operation. If the return line and regulator are functioning correctly have the HC dosing pump and pressure sensor tested. A clogged dosing injector creating back pressure should also be evaluated.
It means the fuel pressure in the aftertreatment hydrocarbon dosing system has exceeded the maximum acceptable threshold, indicating a problem with pressure regulation in the HC dosing circuit.
The most common causes are a faulty pressure regulator, a blocked HC dosing fuel return line, a failing dosing pump delivering excessive pressure, or a clogged dosing injector creating pressure buildup.
Short distances may be possible but excessive HC dosing fuel pressure risks damaging lines, fittings, and the dosing injector. Address this fault promptly.
It can if the high pressure condition affects HC dosing injector operation and prevents active regeneration from completing, leading to soot accumulation and DPF related derate codes.
Inspect the fuel return line and pressure regulator for the HC dosing system. Have the dosing pump and injector tested. Once pressure returns to the normal operating range 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.