Fault code 3251, also known as SPN 3610 FMI 0 or SPN 3610 FMI 16, is more than just a warning light on your dashboard—it's a critical signal that the Diesel Oxidation Catalyst (DOC) intake temperature has exceeded its maximum allowable limit.
Ignoring this issue can lead to decreased performance and potentially costly damage. Understanding what this fault code means, why it occurs, and how to address it is essential for maintaining your truck's efficiency and reliability. Let’s break it down and ensure you’re equipped to handle this challenge head-on.
What is fault code 3251?
This fault code signals that the DOC intake temperature sensor has detected temperatures exceeding 1382°F (750°C) for more than 10 seconds. When this happens, your truck's Engine Control Module (ECM) will illuminate the red stop engine lamp or the malfunction indicator lamp (MIL) immediately.
The DOC intake temperature sensor is crucial for monitoring the temperature of exhaust gases entering the Diesel Oxidation Catalyst. The ECM converts the voltage from the sensor into a temperature reading, ensuring that the after-treatment system operates within safe parameters.
The DOC intake temperature sensor is located on the after-treatment DOC, specifically positioned to measure the temperature of the exhaust gases entering the DOC.
This diagnostic runs continuously while the engine is running, ensuring constant monitoring of the DOC intake temperature. The ECM sets fault code 3251 when it detects that the DOC intake temperature sensor has recorded temperatures above 1382°F (750°C) for more than 10 seconds. This prolonged high temperature can indicate severe issues within the after-treatment system.
What happens when this fault code is active?
When fault code 3251 is active, the ECM takes immediate action to protect the engine and after-treatment system. It illuminates the red stop engine lamp and the MIL light and may reduce engine performance to prevent further damage.
How to reset fault code 3251:
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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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Degraded, diluted, or incorrect diesel exhaust fluid
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Malfunctioning DOC intake temperature sensor
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Upstream exhaust system malfunctions
Addressing these issues promptly is critical to prevent further damage and ensure compliance with emission standards. If you have OTR Diagnostics, you can use this powerful tool to perform all OEM fault code resets, after-treatment maintenance, and regens.
For those who don’t have it yet, OTR Diagnostics is designed to provide you with all the necessary information for your engine. It empowers you to take full ownership of your fault code information, making maintenance easier and more efficient.
With OTR Diagnostics, you gain the power to take control of your truck’s performance and avoid costly downtime. Fault code 3251, or SPN 3610 FMI 0/16, is a reminder of the importance of prompt action and proactive care.
By addressing this issue early, performing regular maintenance, and using high-quality diesel exhaust fluid, you can keep your truck operating at its best. Ready to dive deeper into keeping your truck road-ready?
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