Cummins fault code6977 · Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit
Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit - Special Instructions
6977 Cummins fault code as shown in INSITE / CaltermSPN3361 · Aftertreatment 1 Diesel Exhaust Fluid Dosing UnitFMI14 Special instructionsOBD codenone (J1939 only)LampRed STOP lampCummins textAftertreatment 1 Diesel Exhaust Fluid Dosing Unit - Special InstructionsFailure modeSpecial InstructionsWhat Cummins code 6977 means
The ECM has logged Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit with a special instruction. The exact meaning is specific to this fault code in the Cummins troubleshooting manual rather than a generic electrical failure mode.
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 3361 FMI 14 rather than as Cummins code 6977. Cummins INSITE and Calterm show the Cummins number, the SPN / FMI pair and the lamp together.
This is an emissions-system code. If the component it refers to has been removed or unplugged (DPF, EGR, SCR / DEF or NOx sensor delete) the code will keep returning and the derate with it, however many times it is cleared, because the diagnostic is still enabled in the calibration. The lasting fix in that case is to disable the fault in the .xcal itself.
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 3361 Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit
18 other fault codes share this SPN; each one is a different failure mode (FMI) of the same component.
Related Cummins fault codes
J1939 failure mode identifiers (FMI)
FMI 14 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 6977
What does Cummins fault code 6977 mean?
Cummins 6977 is "Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit - Special Instructions". It maps to SPN 3361 FMI 14. The ECM has logged Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit with a special instruction. The exact meaning is specific to this fault code in the Cummins troubleshooting manual rather than a generic electrical failure mode.
Which lamp does fault code 6977 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 6977?
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 6977 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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