Cummins fault code 3312
DPF Outlet Temperature: reading above normal (most severe)
What it means
Cummins' description: Aftertreatment 1 Diesel Particulate Filter Outlet Temperature - Data valid but above normal operation.
SPN 3246 is Aftertreatment 1 Diesel Particulate Filter Outlet Gas Temperature. 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
- 3255 SPN 3246 FMI 16
DPF Outlet Temperature: reading above normal (moderately severe) - 3256 SPN 3246 FMI 15
DPF Outlet Temperature: reading above normal (least severe) - 3319 SPN 3246 FMI 3
DPF Outlet Temperature Sensor Circuit: circuit voltage high / shorted high - 3321 SPN 3246 FMI 4
DPF Outlet Temperature Sensor Circuit: circuit voltage low / shorted low - 3322 SPN 3246 FMI 2
DPF Outlet Temperature: erratic or intermittent signal
Related DPF codes
- 3311 SPN 3242 FMI 0
DPF Intake Temperature: reading above normal (most severe) - 3316 SPN 3242 FMI 4
DPF Intake Temperature Sensor Circuit: circuit voltage low / shorted low - 3317 SPN 3242 FMI 3
DPF Intake Temperature Sensor Circuit: circuit voltage high / shorted high - 3318 SPN 3242 FMI 2
DPF Intake Temperature: erratic or intermittent signal - 3254 SPN 3242 FMI 15
DPF Intake Temperature: reading above normal (least severe) - 3253 SPN 3242 FMI 16
DPF Intake Temperature: reading above normal (moderately severe)
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 3312 mean?
Cummins fault code 3312 is J1939 SPN 3246 FMI 0: Aftertreatment 1 Diesel Particulate Filter Outlet Temperature - Data valid but above normal operation. In plain terms: dpf outlet temperature: reading above normal (most severe).
Can I keep driving with Cummins code 3312?
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 3312?
SPN 3246 identifies the part or system (Aftertreatment 1 Diesel Particulate Filter Outlet Gas Temperature). FMI 0 describes the type of failure: reading above normal (most severe).
What usually causes Cummins code 3312?
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.