Fault code 3712, also known as SPN 5246 FMI 5, isn’t just another alert—it’s a serious warning that demands immediate attention. This critical fault code signals prolonged SCR (Selective Catalytic Reduction) system issues, which, if left unresolved, can lead to significant performance problems and costly repairs.
Understanding what this fault code means, why it occurs, and how to address it is vital for keeping your truck in top shape and avoiding potential downtime. Let’s dive into the details so you can stay ahead of the problem and keep your truck running strong.
What is fault code 3712?
This fault code signals that there are critical Selective Catalytic Reduction (SCR)-related fault codes that have been active for an extended period. This indicates severe issues within the SCR system that must be addressed immediately.
The SCR system is designed to reduce nitrogen oxide emissions from the engine exhaust and relies on several components working together, including the DEF system, the SCR catalyst, and NOx sensors. Any prolonged issue within the system can lead to significant performance and emission problems.
The components of the SCR system are located throughout the exhaust system. This includes both the inlet and outlet NOx sensors, the DEF injector, and the SCR catalyst. These are all critical parts of the system, and a fault within any of these can trigger fault code 3712.
This diagnostic runs continuously while the engine is operating. It monitors the health of the SCR system and ensures that NOx reduction is occurring as expected. The ECM sets this fault code 3712 when it detects that critical SCR-related fault codes have been active for an extended period. This prolonged activity indicates that the issues are severe and must be resolved to prevent further damage.
What happens when this fault code is active?
When this fault code is active, the ECM takes immediate action to protect the engine and after-treatment system. It activates the red stop engine lamp and the MIL light and reduces engine power to minimize further damage.
How to reset fault code 3712:
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Perform a key cycle: Turn the engine off, wait 1 minute, then start it again and let the engine idle for 1 minute.
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The fault code status displayed by OTR Diagnostics will change to inactive after the diagnostic run passes.
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You can also use OTR Diagnostics to clear the MIL or check the status of the fault code.
Possible causes for this fault code include:
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Faulty inlet and outlet NOx sensors
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Issues with the DEF system
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Malfunctioning SCR catalyst
Promptly addressing fault code issues is essential to prevent further damage, ensure emission compliance, and maintain your truck’s performance. With OTR Diagnostics, you have a powerful tool at your fingertips to perform OEM resets, after-treatment maintenance, and regens—all designed to keep your truck running efficiently.
For those who don’t yet have OTR Diagnostics, it’s your ultimate resource for understanding fault codes and taking control of your engine’s maintenance.
Don’t wait for small issues to turn into costly repairs. Regular maintenance, paired with high-quality diesel exhaust fluid and the insights from OTR Diagnostics, helps you stay ahead.
Learn more about OTR Diagnostics or explore our other blogs for expert tips and solutions!
