Cummins 4155 Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit Heater Relay Circuit - Voltage Above Normal or Shorted to High Source
What this code means
Cummins fault code 4155 (SPN 5746 / FMI 3) refers to: Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit Heater Relay Circuit - Voltage Above Normal or Shorted to High Source. It is logged by the engine control module (ECM) on Cummins-powered vehicles and read over the J1939 diagnostic network.
Emissions system
This is an emissions after-treatment related fault on the SCR & DEF system. On Cummins-powered vehicles it is commonly seen when that after-treatment system is faulty, restricted, or has been modified.
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Frequently asked questions
Cummins fault code 4155 (SPN 5746 / FMI 3) indicates aftertreatment 1 diesel exhaust fluid dosing unit heater relay circuit - voltage above normal or shorted to high source.
Cummins 4155 is generally treated as a moderate-severity fault. Have the engine and its wiring inspected, and confirm the reading with a J1939 diagnostic scan before clearing the code.
Yes. Cummins 4155 is associated with the SCR & DEF after-treatment system on Cummins engines.
