SPN 3720: DPF ash load
Ash builds up in the DPF over thousands of hours and does not burn off in a regen. Type another SPN and FMI to check it.
Ash builds up in the DPF over thousands of hours and does not burn off in a regen. A high ash load means the filter is due to be pulled and cleaned or swapped.
- Plan a DPF clean or exchange.
- Check oil use: an engine burning oil fills the filter with ash faster.
- Run low-ash oil (API CK-4).
Paste the whole line if you like: "SPN 3251 FMI 0", "3251/0" or Deere's "003251.00". Plain-words guidance; the service manual wins.
What SPN 3720 means
Ash builds up in the DPF over thousands of hours and does not burn off in a regen. A high ash load means the filter is due to be pulled and cleaned or swapped.
How urgent it is
Schedule it. Put it on the next service. Watch for it to come back.
What to check first
- Plan a DPF clean or exchange.
- Check oil use: an engine burning oil fills the filter with ash faster.
- Run low-ash oil (API CK-4).
Plain-words guidance for a foreman, not a repair procedure. Makers add their own codes and steps; the machine's service manual wins.
Other FMIs for SPN 3720
| Code | What failed | Urgency |
|---|---|---|
| SPN 3720 FMI 0 | above normal, most severe | Fix it today |
| SPN 3720 FMI 2 | erratic or intermittent | Fix it today |
| SPN 3720 FMI 15 | above normal, least severe | Schedule it |
| SPN 3720 FMI 16 | above normal, moderately severe | Schedule it |
Next time, Dozer catches the code when it fires.
Plug a CAN logger into the machine's J1939 port, or connect the telematics you have. When a code fires, Dozer opens a repair ticket with the meaning, how urgent it is and what to check.
- The code, the machine and its hours on one ticket
- Severity sorted: keep working, plan a stop, or stop now
- The mechanic gets the checklist before they drive out
- Repeat codes on the same machine get flagged
LIVE EX-04 · SPN 3251 FMI 0 · plan a stop today Photo is an AI-generated stand-in, not a customer site.
Email me the PDF
We'll send this to you as a PDF, plus a reminder if there's a date in it. One email, no list.
We use it to send this and nothing else. See privacy.
Questions crews ask
What does SPN 3720 mean?
Ash builds up in the DPF over thousands of hours and does not burn off in a regen. A high ash load means the filter is due to be pulled and cleaned or swapped.
Can I keep running with SPN 3720?
Schedule it. It can wait for a planned stop, but don't let it ride for weeks. If the machine derates or the stop lamp is on, stop.
What should I check first for SPN 3720?
Plan a DPF clean or exchange. Check oil use: an engine burning oil fills the filter with ash faster. Run low-ash oil (API CK-4).
How do I clear SPN 3720?
Fix the cause first. Most codes go inactive by themselves once the condition is gone and the engine has run a key cycle or two. Clearing it with a service tool without a fix only hides it until it comes back.
Which machines show SPN 3720?
Any diesel that speaks SAE J1939: excavators, dozers, loaders, haul trucks, generators and on-road trucks with Cat, Cummins, Deere, Komatsu, Volvo, Kubota, Perkins and other engines. The SPN means the same thing on all of them; the fix steps can differ, so check the service manual.
Your site at 6 a.m., before you're there.
Free for one site and one camera. $99 a site after. Crew is always free. 7 days of everything free, no card.