Cummins Fault Code

Free · no signup

Cummins 3712 (SPN:5246 / FMI:0)

Final Derate / 5 MPH Limit.

System

Aftertreatment

Symptom

Final Derate / 5 MPH Limit.

Diagnosis & fix steps

LOGIC: Regulatory Inducement—SCR system failure has been ignored for too long. ACTION: Resolve the "root cause" code (e.g., DEF quality or NOx sensor) and perform a "Stationary Regeneration" or "SCR Crystalization Reset."

Red Seal field insights

Red Seal Fix: You cannot "clear" this code by just unhooking the batteries. The ECM has a timer that must be satisfied. Usually, you need to fix the secondary fault (like SPN 6254) and then run the engine at high exhaust temps to prove the SCR is working again.

Same code keeps coming back?

That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.

Book an uptime review

Read before you touch anything

  • This is general reference information, not a repair manual. It is for trained, qualified technicians.
  • Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
  • Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
  • You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
  • Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.

Track this across your whole fleet

This code is free to read. AM Fleet Integrity lets your team log fault codes against assets, plus the full fault-code library, QR operator reporting, PM scheduling and predictive alerts. Start free — no credit card required.

Start your free trial

Related Cummins fault codes

← All Cummins fault codes