Cummins fault code426 · J1939 Network #1
J1939 Network #1 - Data Erratic, Intermittent, or Incorrect
426 Cummins fault code as shown in INSITE / CaltermSPN639 · J1939 Network #1FMI2 Data erratic, intermittent or incorrectOBD codeU0002LampNo lampCummins textJ1939 Network #1 - Data Erratic, Intermittent, or IncorrectFailure modeData Erratic, Intermittent, or IncorrectWhat Cummins code 426 means
The ECM is receiving a signal for J1939 Network #1, but the value jumps around, drops out, or does not agree with other sensors it is checked against. Typical causes are a chafed harness, a corroded connector pin, a failing sensor, or, for a datalink value, another module sending bad data.
No dash lamp is attached to this code in the Cummins fault table. It is logged in the ECM and shows up in Cummins INSITE (or any J1939 tool reading DM1 / DM2), but on its own it does not light a lamp.
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 639 FMI 2 rather than as Cummins code 426; an OBD-II reader shows it as U0002. Cummins INSITE and Calterm show the Cummins number, the SPN / FMI pair and the lamp together.
Fault code 426 is defined in the fault tables of the Cummins calibrations we have analysed, so it is a real, current code rather than a legacy number.
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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 639 J1939 Network #1
14 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 2 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 426
What does Cummins fault code 426 mean?
Cummins 426 is "J1939 Network #1 - Data Erratic, Intermittent, or Incorrect". It maps to SPN 639 FMI 2 and OBD code U0002. The ECM is receiving a signal for J1939 Network #1, but the value jumps around, drops out, or does not agree with other sensors it is checked against. Typical causes are a chafed harness, a corroded connector pin, a failing sensor, or, for a datalink value
Which lamp does fault code 426 turn on?
No lamp: No dash lamp is attached to this code in the Cummins fault table. It is logged in the ECM and shows up in Cummins INSITE (or any J1939 tool reading DM1 / DM2), but on its own it does not light a lamp.
How do I clear or permanently delete Cummins code 426?
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 426 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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