Cummins fault code 3712 indicates an issue with the Selective Catalytic Reduction (SCR) system, specifically “Aftertreatment SCR Operator Inducement – Data Valid but Above Normal Operational Range – Most Severe Level.” This often occurs alongside fault code 3714, which signals “Engine Protection Torque Derate – Condition Exists,” and results in derate mode. This means the engine’s power is reduced to protect it from further damage.
This article explores a real-world case study involving a 2017 Cummins ISB 6.7L engine experiencing these persistent fault codes. Initially, a suspected faulty particulate sensor was replaced, resolving the initial issue that triggered the codes. However, codes 3712 and 3714 remained, despite passing subsequent regeneration and SCR tests.
According to Cummins documentation, both fault codes should clear once all other active fault codes are addressed. Code 3712 triggers the red STOP ENGINE lamp, while 3714 illuminates the amber CHECK ENGINE lamp. These lamps should turn off automatically once the diagnostic tests pass. However, in this specific instance, no other fault codes were present.
The persistent nature of these codes, even after addressing the root cause and passing diagnostic tests, points towards a potential software issue within the Engine Control Module (ECM). The solution in this case involved reflashing the ECM with the latest calibration. This process updates the ECM’s software, essentially resetting it and resolving the underlying software glitch that prevented the codes from clearing.
Reflashing the ECM successfully eliminated both the 3712 and 3714 fault codes, restoring the engine to normal operation. This case highlights that even after seemingly successful repairs and diagnostic tests, persistent 3712 and 3714 codes may require an ECM reflash to address underlying software problems. This procedure has proven effective even when reinstalling the same calibration on ECMs without available updates. This suggests a potential for latched codes and inherent software issues that can be resolved through a software refresh.
