Cummins
Cummins fault code
SPN 629 / FMI 12
Cummins Fault Code 343: Engine Control Module - Warning internal hardware failure
343 on Cummins engines means: Engine Control Module - Warning internal hardware failure. The failure mode (FMI 12) is “bad intelligent device or component”.
Lamp: Yellow
Engine may continue to run, but must be repaired the same day.
Code details
- Manufacturer
- Cummins
- Applies to
- Cummins QS-series electronic engines
- Fault code
- 343
- J1939 SPN
- 629
- FMI
- 12 — Bad intelligent device or component
- J1587 PID / SID
- S254
- Engine models
- QSM11, QSX15, QSK19, QSK23, QST30
- QSK45/60/78 severity level
- QSK45: 4 • QSK60: 4 • QSK78: 4
What to do next
- Read active and inactive codes with the OEM service tool and note the occurrence count.
- FMI 12 tells the shop the type of failure to test for: bad intelligent device or component.
- Have a heavy-duty diesel technician confirm the fault against the engine or chassis service manual before replacing parts.
Get this code diagnosed
Send one request and nearby diesel shops and mobile mechanics can quote the repair.
Owner-OperatorAdd this truck & start trial
Run your own truck?
Log maintenance, track fault codes, and get roadside breakdown dispatch.
$39.99/mo
Cancel anytime
More ways Repairius keeps vehicles running
Tools for owner-operators, shops, fleets and drivers — all in one place.
Auto & Truck Shop OS
From $99.99/mo- Work orders & job management
- Digital vehicle inspections
- Parts lookup & inventory
- Estimates, invoices & payments
Fleet Maintenance
From $129/mo- Preventive maintenance schedules
- Driver DVIRs & defect reports
- Safety & compliance clearance
- Preferred shop dispatch & approvals
My Garage
100% free- Digital glovebox for your vehicles
- Maintenance history & reminders
- Recall alerts
- Book verified local shops
Owner-Operator? Track this truck for $39.99/mo
StartFix these trucks? Get your shop listed free·Find a diesel shop
Related fault codes
- Cummins Fault Code 111 — Engine Control Module – Critical internal failure
- Cummins Fault Code 375 — Fuel Pump Control Module, Electronic Calibration Code Error
- PACCAR Fault Code P060C — Internal ECU Injector Power Generation – Malfunction
- PACCAR Fault Code P1601 — PCI ECU – Internal Error
- PACCAR Fault Code P160A — PCI ECU – Internal Error
- PACCAR Fault Code P060A — PCI ECU – Internal Error
- PACCAR Fault Code P1602 — PCI ECU – Software Error
- PACCAR Fault Code P1658 — PCI ECU – Internal Error
Source: Cummins "Diagnostic Fault Codes For Cummins Engines", publication 80-1044 Rev 5/2013, page 10. See also OBD-II codes.