Cummins fault code3947 · DCS Hardware Configuration Fault
DCS Hardware Configuration Fault - Condition Exists
3947 Cummins fault code as shown in INSITE / CaltermSPN520535 · DCS Hardware Configuration FaultFMI31 Condition existsOBD codenone (J1939 only)LampRed STOP lampCummins textDCS Hardware Configuration Fault - Condition ExistsFailure modeCondition ExistsWhat Cummins code 3947 means
This is not an electrical fault on a sensor. FMI 31 means the ECM has detected that the named condition for DCS Hardware Configuration Fault is true. The fault code itself is the message; the fix is to find out why the ECM believes the condition exists.
It turns on the red STOP ENGINE lamp. Cummins classes this as a fault that can damage the engine or aftertreatment if ignored: stop as soon as it is safe to do so. Many calibrations also apply an engine-protection derate while the fault is active.
On a generic J1939 scan tool, or on the dash of a Freightliner, Kenworth, Peterbilt, International or Volvo chassis, the same fault is shown as SPN 520535 FMI 31 rather than as Cummins code 3947. Cummins INSITE and Calterm show the Cummins number, the SPN / FMI pair and the lamp together.
Custom DTC delete, up to 30 codes, $150. Full DPF / EGR / SCR delete with all related codes and derates, $500. Upload your Calterm .xcal, tick the services, pay with PayPal, and the finished file comes back by email and WhatsApp.
Upload your .xcal →Cummins ECFG / E2M definitions for CM550, CM552, CM554, CM570, CM800, CM850, CM870, CM871 and more: the fault table, torque, fuelling, boost, EGR, DPF and SCR maps, ready for Calterm or WinOLS. Instant download.
Find your ECFG →Other Cummins codes on SPN 520535 DCS Hardware Configuration Fault
Code 3947 is the only Cummins fault code assigned to SPN 520535.
Related Cummins fault codes
J1939 failure mode identifiers (FMI)
FMI 31 is highlighted. The FMI is the second half of every J1939 fault and tells you how the component failed; the SPN tells you which component.
| FMI | Meaning (SAE J1939-73) |
|---|---|
| 0 | Data valid but above normal operational range - most severe level |
| 1 | Data valid but below normal operational range - most severe level |
| 2 | Data erratic, intermittent or incorrect |
| 3 | Voltage above normal, or shorted to high source |
| 4 | Voltage below normal, or shorted to low source |
| 5 | Current below normal or open circuit |
| 6 | Current above normal or grounded circuit |
| 7 | Mechanical system not responding or out of adjustment |
| 8 | Abnormal frequency, pulse width or period |
| 9 | Abnormal update rate |
| 10 | Abnormal rate of change |
| 11 | Root cause not known |
| 12 | Bad intelligent device or component |
| 13 | Out of calibration |
| 14 | Special instructions |
| 15 | Data valid but above normal operating range - least severe level |
| 16 | Data valid but above normal operating range - moderately severe level |
| 17 | Data valid but below normal operating range - least severe level |
| 18 | Data valid but below normal operating range - moderately severe level |
| 19 | Received network data in error |
| 20 | Data drifted high |
| 21 | Data drifted low |
| 22 | Reserved for SAE assignment |
| 23 | Reserved for SAE assignment |
| 24 | Reserved for SAE assignment |
| 25 | Reserved for SAE assignment |
| 26 | Reserved for SAE assignment |
| 27 | Reserved for SAE assignment |
| 28 | Reserved for SAE assignment |
| 29 | Reserved for SAE assignment |
| 30 | Reserved for SAE assignment |
| 31 | Condition exists |
Questions about code 3947
What does Cummins fault code 3947 mean?
Cummins 3947 is "DCS Hardware Configuration Fault - Condition Exists". It maps to SPN 520535 FMI 31. This is not an electrical fault on a sensor. FMI 31 means the ECM has detected that the named condition for DCS Hardware Configuration Fault is true. The fault code itself is the message; the fix is to find out why the ECM believes the condition exists.
Which lamp does fault code 3947 turn on?
Red STOP lamp: It turns on the red STOP ENGINE lamp. Cummins classes this as a fault that can damage the engine or aftertreatment if ignored: stop as soon as it is safe to do so. Many calibrations also apply an engine-protection derate while the fault is active.
How do I clear or permanently delete Cummins code 3947?
An active code goes inactive on its own once the condition is gone; the inactive record stays in the ECM fault history until it is cleared with Cummins INSITE (or a J1939 tool that supports the DM3 / DM11 clear). If the code keeps coming back because the part is gone, disconnected or not worth repairing, the lasting fix is to disable fault 3947 in the calibration: upload your .xcal to the ECFG Superstore file service, custom DTC delete from $150 (up to 30 codes), full DPF / EGR / SCR delete $500, and flash the returned file with Calterm or INSITE.
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