Cummins fault code8491 · HVESS Cell Temperature Differential Status
HVESS Cell Temperature Differential Status - Data Valid But Above Normal Operating Range - Most Severe Level
8491 Cummins fault code as shown in INSITE / CaltermSPN8078 · HVESS Cell Temperature Differential StatusFMI0 Data valid but above normal operational range - most severe levelOBD codenone (J1939 only)LampNo lampCummins textHVESS Cell Temperature Differential Status - Data Valid But Above Normal Operating Range - Most Severe LevelFailure modeData Valid But Above Normal Operating Range - Most Severe LevelWhat Cummins code 8491 means
The reading for HVESS Cell Temperature Differential Status is believed to be correct, but it has gone above the highest limit in the calibration. This is the most severe of the three "above range" levels (FMI 15, 16 and 0), so the ECM is reporting a real operating problem rather than a wiring fault.
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 8078 FMI 0 rather than as Cummins code 8491. Cummins INSITE and Calterm show the Cummins number, the SPN / FMI pair and the lamp together.
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Find your ECFG →Other Cummins codes on SPN 8078 HVESS Cell Temperature Differential Status
2 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 0 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 8491
What does Cummins fault code 8491 mean?
Cummins 8491 is "HVESS Cell Temperature Differential Status - Data Valid But Above Normal Operating Range - Most Severe Level". It maps to SPN 8078 FMI 0. The reading for HVESS Cell Temperature Differential Status is believed to be correct, but it has gone above the highest limit in the calibration. This is the most severe of the three "above range" levels (FMI 15, 16 and 0), so the ECM is reporting a real
Which lamp does fault code 8491 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 8491?
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 8491 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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