The Cummins ISB 6.7L engine, renowned for its power and reliability, can sometimes present challenges with diagnostic trouble codes (DTCs). Two such codes, 3712 and 3714, often appear together and can cause significant frustration for owners and technicians. This article will delve into the meaning of these codes, their common causes, and effective clearing procedures.
Decoding 3712 and 3714
Code 3712 – Aftertreatment SCR Operator Inducement – Data Valid but Above Normal Operational Range – Most Severe Level: This code indicates a problem with the Selective Catalytic Reduction (SCR) system, responsible for reducing harmful NOx emissions. The “Data Valid but Above Normal” signifies that the SCR system is functioning, but a critical parameter is exceeding its acceptable operating range. The “Most Severe Level” designation highlights the urgency of addressing this issue.
Code 3714 – Engine Protection Torque Derate – Condition Exists: This code signals that the engine’s Electronic Control Module (ECM) has activated a torque reduction strategy to protect the engine from potential damage. This “derate” mode limits engine power and performance. Code 3714 often accompanies other DTCs that point to the root cause of the derate condition.
These codes, particularly when occurring together, frequently indicate a problem within the aftertreatment system. Replacing a faulty particulate sensor, as in the case study below, is a common initial step.
Case Study: 2017 ISB 6.7L – Persistent 3712 and 3714 Codes
A 2017 ISB 6.7L presented with persistent 3712 and 3714 codes, even after replacing a faulty particulate sensor. Despite a successful regeneration and SCR test, indicating normal operating temperatures and functionality, the codes refused to clear. The engine remained in derate mode. Further diagnostics revealed no other active fault codes.
Resolution: ECM Reflash
Since all other potential causes were eliminated, a software issue within the ECM was suspected. Reflashing the ECM with the latest calibration successfully resolved the issue. Both the 3712 and 3714 codes were cleared, and the engine resumed normal operation. This suggests that the original codes were “latched” due to a software glitch. Reinstalling the same calibration has also proven effective in similar situations where an update is not available.
Clearing 3712 and 3714: Key Considerations
Both 3712 and 3714 are designed to become inactive once the underlying issue triggering them is addressed. This typically involves:
- Thorough Diagnostics: Utilize diagnostic tools to pinpoint the root cause.
- Component Replacement: Replace any faulty sensors or components within the aftertreatment system, such as the particulate matter sensor or NOx sensors.
- System Regeneration: Perform a manual regeneration of the aftertreatment system.
- ECM Reflash/Update: Update the ECM software to the latest available calibration to address potential software glitches.
Conclusion
Cummins ISB 6.7L engine codes 3712 and 3714 often signal problems within the aftertreatment system. While component replacement and system regeneration are common solutions, addressing underlying software issues through an ECM reflash may be necessary for successful code clearance. Remember, thorough diagnostics are crucial for accurate and efficient troubleshooting.
