Experiencing a check engine light on your Sprinter van can be unsettling, especially when accompanied by error codes that seem cryptic. Among these, the P20e8 code is a relatively common issue that owners may encounter. This article delves into the P20E8 fault code, specifically focusing on its implications for Sprinter vans and how to approach troubleshooting.
The user of a 2010 Sprinter 2500 Passenger with a 6-cylinder engine reported encountering the P20E8 code. Despite the code being present for several weeks and thousands of kilometers, there were no accompanying symptoms like a DEF low warning, start countdown, or power loss. This scenario suggests that while the system detects an anomaly, the vehicle is still operating within acceptable parameters, at least for basic functionality.
Understanding the P20E8 Code: “Reductant Flow Too Low”
The P20E8 diagnostic trouble code (DTC) technically translates to “Reductant Flow Too Low.” In the context of a diesel Sprinter van, “reductant” refers to Diesel Exhaust Fluid (DEF), also known as AdBlue. This fluid is crucial for the Selective Catalytic Reduction (SCR) system, which is designed to reduce harmful NOx emissions from diesel engines. The P20E8 code indicates that the system is detecting insufficient DEF flow, which could stem from various components within the DEF delivery system.
Potential Causes of the P20E8 Code in Sprinter Vans
Several components could be responsible for triggering the P20E8 code in your Sprinter. Based on the user’s initial assessment and common issues, the primary suspects include:
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DEF Pump Malfunction: The DEF pump is responsible for delivering DEF from the tank to the injector. A failing pump, or one that is working intermittently, could result in reduced flow and trigger the P20E8 code. The user in the original post noted an intermittent humming sound possibly originating from the DEF pump area, which could be a significant clue pointing towards a pump issue.
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DEF Injector Problems: The DEF injector nozzle sprays DEF into the exhaust stream. A clogged or malfunctioning injector can restrict DEF flow, leading to the P20E8 code.
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DEF Supply Module Issues: The DEF module controls the DEF pump and monitors system parameters. A fault within the module itself could disrupt the proper operation of the DEF delivery system.
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DEF Heater Issues (Less Likely in this Scenario): While DEF heater problems are common in Sprinters, they are less directly linked to the P20E8 code. However, extreme cold or heater malfunctions could theoretically affect DEF viscosity and flow, indirectly contributing to the issue in some unusual circumstances. Given the user reports no DEF low warning and fluid level is okay, heater issues are less probable but not entirely ruled out without further investigation.
Diagnosing the P20E8 Code: Step-by-Step Approach
Troubleshooting the P20E8 code requires a systematic approach to pinpoint the root cause. Here’s a step-by-step guide you can follow:
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Initial OBD Scan: As the user did, using an OBD-II scanner is the first step. Confirm that P20E8 is indeed the only code present. Note if it’s pending, stored, or permanent, as this can sometimes offer clues about the intermittency or severity of the issue.
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Check DEF Fluid Level and Quality: Although the user mentioned the DEF level is okay, it’s crucial to double-check. Also, ensure the DEF fluid is not contaminated or old, though this is less likely to directly cause a “flow too low” issue.
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Listen for DEF Pump Operation: Turn the ignition to the “ON” position (without starting the engine) and listen near the DEF tank area for the DEF pump to activate. You should typically hear a brief humming or whirring sound as the pump primes the system. The intermittent humming reported by the user is a critical observation here. If the pump sound is weak, erratic, or absent, it strongly suggests a pump problem.
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Visual Inspection (If Accessible): If you can safely access the DEF pump and lines, visually inspect for any leaks, damage, or loose connections.
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Professional Diagnostic Steps (Recommended): For a more in-depth diagnosis, especially if you are not comfortable working on the DEF system yourself, professional diagnostic tools are invaluable. A qualified mechanic can:
- Use advanced scan tools to monitor live DEF system parameters, including pump pressure and injector activation.
- Perform DEF pump flow tests to measure the actual DEF delivery rate.
- Actuate the DEF injector to check for proper spray pattern and volume.
- Inspect the DEF module for any fault codes or communication issues.
Resolving the P20E8 Code and Restoring DEF System Functionality
Once the faulty component is identified, replacement is usually the necessary step. As the user noted, DEF pump, injector, and module replacement costs can vary. Starting with the most likely culprit based on diagnostic findings (like the humming pump sound in the original case) is a practical approach.
Important Considerations:
- Genuine Parts vs. Aftermarket: When replacing DEF system components, especially critical ones like the pump and module, consider using genuine OEM parts or reputable aftermarket brands to ensure compatibility and reliability.
- System Bleeding/Priming: After replacing any DEF system component, it’s often necessary to bleed or prime the system to remove air and ensure proper DEF flow. Consult your Sprinter service manual or a professional for the correct procedure.
- Code Clearing and System Reset: After repair, clear the P20E8 code using an OBD-II scanner. In some cases, a system reset or adaptation procedure might be required, which may necessitate a more advanced scan tool.
Conclusion: Addressing the P20E8 Code for Optimal Sprinter Performance
The P20E8 code on a Sprinter van signals a “Reductant Flow Too Low” condition within the DEF system. While not always immediately critical to basic vehicle operation, neglecting this code can lead to more significant emissions system issues down the line and potentially affect long-term performance and regulatory compliance. By understanding the potential causes, following a systematic diagnostic approach, and addressing the faulty component, you can effectively resolve the P20E8 code and ensure your Sprinter’s DEF system operates as intended. If you’re uncertain about any step, seeking professional diagnosis and repair is always the recommended course of action.
