Cummins ISB4.5 CM2150 Fault Code: 3532 PID: SPN: 171 FMI: 19 Ambient Air Temperature – Received Network Data In Error.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
Normally, switches, accelerators, and other components are connected to the engine control module (ECM) directly through individual wires. Multiplexing allows those same components to be hard wired to an original equipment manufacturer (OEM) vehicle electronic control unit (VECU) or transmission electronic control unit in the cab. Then component values and states from components (such as sensors, accelerators, and switches) can be transmitted from the OEM VECU to the Cummins® ECM over the Society of Automotive Engineers (SAE) J1939 data link. Messages sent from the OEM VECU or transmission electronic control unit are received by the Cummins® ECM and used for controlling the engine. The Cummins Inc. ECM and OEM VECU must be configured correctly so proper operation of the multiplexed components will occur.

Component Location
The J1939 data link wiring and VECU location varies by OEM. See equipment manufacturer service information for location.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the key switch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes
The OEM VECU determines there is a malfunction of the ambient air temperature sensor.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
-The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
-The “Reset All Faults” command in INSITE™ electronic service tool can be used to clear active and inactive faults.

Shop Talk
The J1939 multiplexing controller has indicated a malfunction of the ambient air temperature sensor.

See the appropriate OEM wiring diagram when troubleshooting circuits utilizing wiring supplied by the OEM.

For intermittent power supply and data link communication issues with aftertreatment components, it is highly recommended that the OEM power distribution center fuses and relays be thoroughly checked for loose, missing, or intermittent connections.

Cummins ISB4.5 CM2150 Fault Code: 3527 PID: 91 SPN: 558 FMI: 19 Accelerator Pedal or Lever Idle Validation Switch – Received Network Data In Error.

Cummins ISB4.5 CM2150 Fault Code: 3526 PID: SPN: 84 FMI: 9 Wheel-Based Vehicle Speed – Abnormal Update Rate.

Cummins ISB4.5 CM2150 Fault Code: 3525 PID: SPN: 84 FMI: 19 Wheel-Based Vehicle Speed – Received Network Data In Error.

Cummins ISB4.5 CM2150 Fault Code: 3492 PID: SPN: 251 FMI: 10 Real Time Clock – Abnormal Rate of Change.

Cummins ISB4.5 CM2150 Fault Code: 3429 PID: SID 254 SPN: 4346 FMI: 5 Aftertreatment Diesel Exhaust Fluid Line Heater 4 Circuit – Current Below Normal or Open Circuit

Cummins ISB4.5 CM2150 Fault Code: 3426 PID: SPN: 4346 FMI: 3 Aftertreatment Diesel Exhaust Fluid Line Heater 4 Circuit – Voltage Above Normal or Shorted to High Source.

WARNING!