← Back to Detroit Diesel Fault Codes
Detroit Diesel SPN 27 FMI 9 indicates that the EGR valve position is not matching the commanded position from the ECM. This code appears on DD13, DD15, and DD16 engines and means the exhaust gas recirculation system is not responding correctly, which can affect emissions control, engine performance, and combustion efficiency.
Symptoms
- Check engine light on
- EGR or emissions warning light illuminated
- Rough idle or unstable engine operation
- Reduced engine performance Engine derate possible Increased
- NOx emissions
- Black smoke from exhaust possible
Cause
This code triggers when the ECM detects a discrepancy between the commanded EGR valve position and the actual position reported by the valve sensor. Common causes include:
Excessive carbon deposits in the EGR system
Carbon buildup on the EGR valve preventing proper movement
Stuck or seized EGR valve
Failed EGR valve position sensor
Damaged EGR valve actuator motor
Wiring or connector fault at the EGR valve
EGR cooler restriction affecting valve operation
Can You Keep Driving?
Limited driving may be possible but an EGR valve position error affects combustion efficiency and emissions control. Engine performance will be impacted and a derate condition may follow if the fault persists. Address this promptly to avoid further carbon buildup or component damage.
Recommended Action
Inspect the EGR valve for carbon buildup and clean if necessary. Check the valve actuator and position sensor for proper operation. Inspect wiring and connectors at the EGR valve for damage or corrosion. If cleaning does not resolve the issue the EGR valve assembly may need to be replaced.
It means the EGR valve is not moving to the position commanded by the ECM, indicating a mechanical, electrical, or carbon buildup issue with the valve or its control system.
The most common causes are carbon buildup preventing valve movement, a stuck or seized EGR valve, a failed position sensor, or a wiring fault at the valve connector.
Short distances may be possible but EGR valve position errors affect combustion and emissions control. A derate condition may follow if not addressed promptly.
Yes. If the ECM cannot control EGR valve position correctly it will trigger derate conditions to limit emissions and protect the engine.
Clean or replace the EGR valve and inspect the position sensor and wiring. Once the valve responds correctly to ECM commands and position feedback matches commanded values the code should clear.
Related codes
Need Immediate Help With This Fault Code?
If your engine is derating, losing power, or unable to complete regeneration, don’t risk further damage or costly downtime.
Use 4RoadService to locate mobile truck repair, dealer diagnostics, or emergency roadside assistance near your location.
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.