Cummins fault code7952 · Aftertreatment 2 SCR Outlet Pressure
Aftertreatment 2 SCR Outlet Pressure - Voltage Below Normal or Shorted to Low Source
7952 Cummins fault code as shown in INSITE / CaltermSPN11776 · Aftertreatment 2 SCR Outlet PressureFMI4 Voltage below normal, or shorted to low sourceOBD codenone (J1939 only)LampAmber WARNING lampCummins textAftertreatment 2 SCR Outlet Pressure - Voltage Below Normal or Shorted to Low SourceFailure modeVoltage Below Normal or Shorted to Low SourceWhat Cummins code 7952 means
The signal wire for Aftertreatment 2 SCR Outlet Pressure is sitting below the voltage window the ECM expects. In practice that is usually a short to ground, a short to the sensor return, a failed sensor, or a missing 5 V supply.
It lights the amber CHECK ENGINE (warning) lamp. The engine keeps running, but a torque or speed derate may apply depending on the calibration and on how long the fault stays 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 11776 FMI 4 rather than as Cummins code 7952. 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 11776 Aftertreatment 2 SCR Outlet Pressure
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 4 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 7952
What does Cummins fault code 7952 mean?
Cummins 7952 is "Aftertreatment 2 SCR Outlet Pressure - Voltage Below Normal or Shorted to Low Source". It maps to SPN 11776 FMI 4. The signal wire for Aftertreatment 2 SCR Outlet Pressure is sitting below the voltage window the ECM expects. In practice that is usually a short to ground, a short to the sensor return, a failed sensor, or a missing 5 V supply.
Which lamp does fault code 7952 turn on?
Amber WARNING lamp: It lights the amber CHECK ENGINE (warning) lamp. The engine keeps running, but a torque or speed derate may apply depending on the calibration and on how long the fault stays active.
How do I clear or permanently delete Cummins code 7952?
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 7952 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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