Cummins 3937 Aftertreatment 1 SCR Intermediate NH3 Sensor - Abnormal Rate of Change
What this code means
Cummins fault code 3937 (SPN 5848 / FMI 10) refers to: Aftertreatment 1 SCR Intermediate NH3 Sensor - Abnormal Rate of Change. 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 3937 (SPN 5848 / FMI 10) indicates aftertreatment 1 scr intermediate nh3 sensor - abnormal rate of change.
Cummins 3937 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 3937 is associated with the SCR & DEF after-treatment system on Cummins engines.
