Cummins fault code 346
ECM: bad device or component
What it means
Cummins' description: Engine Control Module - Warning Software error.
SPN 630 is ECM. FMI 12 means a smart device or module reported that it has failed internally.
The engine ECM talks to the transmission, ABS, dash and aftertreatment modules over the J1939 data network. These codes mean the ECM itself, its calibration, or its communication with other modules has a problem.
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
A network timeout logged once, often during cranking, that cleared.
Schedule a repair
Gauges dropping out, the transmission or ABS acting odd, or codes returning. Book diagnosis. These can go from annoying to stranded quickly.
Stop and get help
Red lamp for an ECM internal failure, or the engine won't start or shuts down. Get it towed or seen where it sits.
Common causes
FMI 12 is an electrical or signal fault, so start with the circuit:
- J1939 network wiring damaged or shorted
- Missing or failed terminating resistor
- Corroded connector at a module
- Another module on the network failed or lost power
- Low battery voltage during cranking
If the circuit checks out, the reading may be real. Other possibilities: eCM calibration doesn't match the vehicle or another module; eCM internal failure.
What you can check before calling
- Note which other systems acted up: gauges, transmission, ABS
- Check for recent electrical work or aftermarket devices plugged into the diagnostic port
- Check batteries and grounds
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers.
Engines and sources
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: Diagnostic Fault Codes for Cummins Engines. Always confirm with Cummins service information (QuickServe) for your engine serial number.
Same SPN, other failure types
Related ECM, network and data link codes
- 343 SPN 629 FMI 12
ECM Warning Internal Hardware Failure: bad device or component - 319 SPN 251 FMI 2
Real Time Clock: erratic or intermittent signal - 299 SPN 1384 FMI 31
Engine Shutdown Commanded by J1939: condition exists - 291 SPN 625 FMI 9
Proprietary Datalink Error (OEM/Vehicle Datalink): abnormal update rate - 288 SPN 974 FMI 19
SAE J1939 Multiplexing Remote Accelerator Pedal or Lever Position Sensor System: network data error - 286 SPN 639 FMI 13
SAE J1939 Multiplexing Configuration Error: out of calibration
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 346 mean?
Cummins fault code 346 is J1939 SPN 630 FMI 12: Engine Control Module - Warning Software error. In plain terms: ecm: bad device or component.
Can I keep driving with Cummins code 346?
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 346?
SPN 630 identifies the part or system (ECM). FMI 12 describes the type of failure: bad device or component.
What usually causes Cummins code 346?
The most common causes are: j1939 network wiring damaged or shorted; missing or failed terminating resistor; corroded connector at a module.
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.