Cummins fault code 1922
DPF Differential Pressure: reading above normal (most severe)
What it means
Cummins' description: Aftertreatment Diesel Particulate Filter Differential Pressure - Data valid but above normal Operating Range.
SPN 3251 is Aftertreatment 1 Diesel Particulate Filter Differential Pressure. FMI 0 means the sensor is working, but the value it reports is far above where it should be. This is the most severe 'high' level.
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
A red stop lamp means Cummins treats this as serious. Stop the engine as soon as you can do it safely and get it checked before running it again.
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. Cummins rates this a red stop lamp code, so if the red lamp is on, go by the red 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
The sensor reading itself is out of range or the condition is real, so look at the system:
- 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
- DPF full of ash and due for cleaning or replacement
- Face-plugged or cracked DOC/DPF
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
- 1879 SPN 3251 FMI 3
DPF Differential Pressure Sensor Circuit: circuit voltage high / shorted high - 1881 SPN 3251 FMI 4
DPF Differential Pressure Sensor Circuit: circuit voltage low / shorted low - 1883 SPN 3251 FMI 2
DPF Differential Pressure Sensor: erratic or intermittent signal - 1921 SPN 3251 FMI 16
DPF Differential Pressure: reading above normal (moderately severe) - 2639 SPN 3251 FMI 15
DPF Differential Pressure: reading above normal (least severe)
Related DPF codes
- 1981 SPN 3936 FMI 15
DPF System: reading above normal (least severe) - 1993 SPN 4795 FMI 31
DPF Missing: condition exists - 2742 SPN 3249 FMI 17
Exhaust Gas Temperature 2: reading below normal (least severe) - 2743 SPN 3249 FMI 18
Exhaust Gas Temperature 2: reading below normal (moderately severe) - 2754 SPN 81 FMI 16
Engine DPF Intake Pressure: reading above normal (moderately severe) - 2777 SPN 3703 FMI 31
Particulate Trap Active Regeneration Inhibited Due to Inhibit Switch: condition exists
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 1922 mean?
Cummins fault code 1922 is J1939 SPN 3251 FMI 0: Aftertreatment Diesel Particulate Filter Differential Pressure - Data valid but above normal Operating Range. In plain terms: dpf differential pressure: reading above normal (most severe).
Can I keep driving with Cummins code 1922?
No. Cummins assigns this code a red stop lamp. Stop the engine as soon as it's safe and have it checked before running it again. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 1922?
SPN 3251 identifies the part or system (Aftertreatment 1 Diesel Particulate Filter Differential Pressure). FMI 0 describes the type of failure: reading above normal (most severe).
What usually causes Cummins code 1922?
The most common causes are: 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.
Diesel down in the Midlands?
We work on Cummins-powered pickups, vans and medium-duty trucks across Lexington, Columbia and the Midlands, on site at your yard or roadside.