Cummins fault code 6551
DPF Outlet Pressure Sensor Circuit: circuit voltage high / shorted high
What it means
Cummins' description: Aftertreatment 1 Diesel Particulate Filter Outlet Pressure Sensor Circuit - Voltage above normal, or shorted to high source.
SPN 3610 is Aftertreatment Diesel Particulate Filter Outlet Pressure. FMI 3 means the voltage on the circuit is higher than possible for a good sensor, usually an open signal wire, a short to a power wire, or a failed sensor.
The DPF traps soot from the exhaust and burns it off during regeneration. Pressure and temperature sensors before and after the filter tell the ECM how loaded the filter is and whether regeneration is working.
What the lamp means
This code normally doesn't turn on a dash lamp. It's logged in the ECM for a technician to see, and often explains another active code.
Green, yellow, red: three ways this can look
The same code can be a quick fix or a reason to shut down. Match your situation to the closest example.
Keep an eye on it
The DPF lamp comes on solid and the truck drives normally. Running it at highway speed for 20-30 minutes, or doing a parked regen if your truck supports it, clears it.
Schedule a repair
The DPF lamp is flashing or the code keeps coming back after regens. Plan service soon. The filter is loading faster than it can clean itself and something upstream may be wrong.
Stop and get help
Stop lamp on, power derated, or a strong exhaust smell or smoke. Don't keep driving. A plugged DPF can overheat, crack, and take the turbo or engine with it.
Common causes
FMI 3 is an electrical or signal fault, so start with the circuit:
- Cracked, melted or disconnected sensor hose (common on differential pressure sensors)
- Damaged connector or chafed harness near the hot exhaust
- Failed pressure or temperature sensor
- Sensor module or 5-volt supply problem
If the circuit checks out, the reading may be real. Other possibilities: too much idling or short trips, so the DPF never gets hot enough to regenerate; regeneration interrupted or inhibited (inhibit switch on, key-off mid regen); upstream problem making excess soot: leaking injector, EGR or boost fault.
What you can check before calling
- Check the dash for a regen or DPF lamp and whether a regen is being requested
- Make sure the regen inhibit switch isn't turned on
- Look at the sensor hoses and wiring on top of the DPF for melted or loose lines
- Note how much the truck idles versus runs at highway speed
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers. For the bigger picture, read our guide: DPF regeneration explained: passive, active and forced.
Engines and sources
Listed by Cummins for: QSB 6.7 (DOC/ DPF+ SCR), QSL 9 (DOC/ DPF+ SCR), QSX 15, QSG 12. Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Cummins Tier 4 Fault Codes. Always confirm with Cummins service information (QuickServe) for your engine serial number.
Same SPN, other failure types
- 3133 SPN 3610 FMI 3
DPF Outlet Pressure Sensor Circuit: circuit voltage high / shorted high - 3134 SPN 3610 FMI 4
DPF Outlet Pressure Sensor Circuit: circuit voltage low / shorted low - 3135 SPN 3610 FMI 2
DPF Outlet Pressure: erratic or intermittent signal - 6552 SPN 3610 FMI 4
DPF Outlet Pressure Sensor Circuit: circuit voltage low / shorted low - 6553 SPN 3610 FMI 2
DPF Outlet Pressure: erratic or intermittent signal
Related DPF codes
- 6568 SPN 3695 FMI 2
Regeneration Inhibit Switch: erratic or intermittent signal - 6596 SPN 3713 FMI 31
DPF Active Regeneration Inhibited Due to System Timeout: condition exists - 6265 SPN 3936 FMI 7
DPF System: not responding / out of adjustment - 5938 SPN 3750 FMI 14
DPF 1 Conditions Not Met for Active Regeneration: special instructions - 4584 SPN 3936 FMI 14
DPF System: special instructions - 4451 SPN 5741 FMI 2
Outlet Soot: erratic or intermittent signal
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does Cummins fault code 6551 mean?
Cummins fault code 6551 is J1939 SPN 3610 FMI 3: Aftertreatment 1 Diesel Particulate Filter Outlet Pressure Sensor Circuit - Voltage above normal, or shorted to high source. In plain terms: dpf outlet pressure sensor circuit: circuit voltage high / shorted high.
Can I keep driving with Cummins code 6551?
Usually, yes. This code doesn't normally turn on a lamp by itself, but check for other active codes that might be more serious. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 6551?
SPN 3610 identifies the part or system (Aftertreatment Diesel Particulate Filter Outlet Pressure). FMI 3 describes the type of failure: circuit voltage high / shorted high.
What usually causes Cummins code 6551?
The most common causes are: cracked, melted or disconnected sensor hose (common on differential pressure sensors); damaged connector or chafed harness near the hot exhaust; failed pressure or temperature sensor.
Diesel down in the Midlands?
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