Cummins fault code7221 · Lost Communication with LIN Communication Bus
Lost Communication with LIN Communication Bus - Abnormal Update Rate
7221 Cummins fault code as shown in INSITE / CaltermSPN521048 · Lost Communication with LIN Communication BusFMI9 Abnormal update rateOBD codenone (J1939 only)LampNo lampCummins textLost Communication with LIN Communication Bus - Abnormal Update RateFailure modeAbnormal Update RateWhat Cummins code 7221 means
The ECM expected Lost Communication with LIN Communication Bus to arrive on the datalink at a regular rate and it is arriving late or not at all. This is a communication fault between modules (J1939 / J1587 wiring, terminating resistors, or a module that is powered down or not responding) rather than a sensor 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 521048 FMI 9 rather than as Cummins code 7221. 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 521048 Lost Communication with LIN Communication Bus
Code 7221 is the only Cummins fault code assigned to SPN 521048.
Related Cummins fault codes
J1939 failure mode identifiers (FMI)
FMI 9 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 7221
What does Cummins fault code 7221 mean?
Cummins 7221 is "Lost Communication with LIN Communication Bus - Abnormal Update Rate". It maps to SPN 521048 FMI 9. The ECM expected Lost Communication with LIN Communication Bus to arrive on the datalink at a regular rate and it is arriving late or not at all. This is a communication fault between modules (J1939 / J1587 wiring, terminating resistors, or a module that is
Which lamp does fault code 7221 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 7221?
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 7221 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.
← All Cummins fault codes · XCAL file service · ECFG Superstore