Cummins fault code 4259
DPF Temperature Sensor Module: root cause not known
What it means
Cummins' description: Aftertreatment Diesel Particulate Filter Temperature Sensor Module - Root Cause Not Known.
SPN 5742 is Aftertreatment Diesel Particulate Filter Temperature Sensor Module. FMI 11 means the ECM detected a fault in this system but can't pin down the exact type. Further testing is needed.
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
An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.
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
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
- 4151 SPN 5742 FMI 9
DPF Temperature Sensor Module: abnormal update rate - 4158 SPN 5742 FMI 12
DPF Temperature Sensor Module: bad device or component - 4161 SPN 5742 FMI 3
DPF Temperature Sensor Module: circuit voltage high / shorted high - 4162 SPN 5742 FMI 4
DPF Temperature Sensor Module: circuit voltage low / shorted low - 4163 SPN 5742 FMI 16
DPF Temperature Sensor Module- Data Valid But Above Normal Operating Range: reading above normal (moderately severe)
Related DPF codes
- 4213 SPN 3695 FMI 2
Regeneration Inhibit Switch: erratic or intermittent signal - 4154 SPN 5747 FMI 4
Outlet Soot Sensor Heater: circuit voltage low / shorted low - 4153 SPN 5747 FMI 3
Outlet Soot Sensor Heater: circuit voltage high / shorted high - 4144 SPN 5741 FMI 4
Outlet Soot Sensor: circuit voltage low / shorted low - 4143 SPN 5741 FMI 3
Outlet Soot Sensor: circuit voltage high / shorted high - 4449 SPN 5747 FMI 10
Outlet Soot Sensor Heater: abnormal rate of change
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 4259 mean?
Cummins fault code 4259 is J1939 SPN 5742 FMI 11: Aftertreatment Diesel Particulate Filter Temperature Sensor Module - Root Cause Not Known. In plain terms: dpf temperature sensor module: root cause not known.
Can I keep driving with Cummins code 4259?
Usually for a short time, if the engine runs normally and no other warnings are on. Get it diagnosed soon, because many amber codes lead to a derate if ignored. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 4259?
SPN 5742 identifies the part or system (Aftertreatment Diesel Particulate Filter Temperature Sensor Module). FMI 11 describes the type of failure: root cause not known.
What usually causes Cummins code 4259?
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.
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