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P249E Mercedes-Benz Code - Closed Loop Reductant Injection Control At Limit - Flow Too High

Quick Answer

The P249E diagnostic trouble code (DTC) for Mercedes-Benz vehicles relates to the Closed Loop Reductant Injection Control system, specifically indicating that the flow rate of the reductant (typically diesel exhaust fluid or AdBlue) is too high. Common causes include Faulty reductant injection control module, Defective reductant flow control valve, Wiring issues or electrical faults in the reductant injection system. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P249E Mercedes-Benz indicates Closed Loop Reductant Injection Control At Limit - Flow Too High.
Common causes
Common causes include Faulty reductant injection control module, Defective reductant flow control valve, Wiring issues or electrical faults in the reductant injection system.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
What is this?
Table of contents Created and updated by William Orellana on Sep 08, 2024
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Code P249E Mercedes-Benz Description

The P249E diagnostic trouble code (DTC) for Mercedes-Benz vehicles relates to the Closed Loop Reductant Injection Control system, specifically indicating that the flow rate of the reductant (typically diesel exhaust fluid or AdBlue) is too high. In modern diesel vehicles, the reductant injection system is crucial for reducing harmful emissions by converting nitrogen oxides (NOx) into harmless nitrogen and water vapor. The reductant injection control system monitors and adjusts the flow of reductant based on various engine operating conditions to ensure efficient emission control.

OBDII Code P249E Mercedes-Benz - Closed Loop Reductant Injection Control At Limit - Flow Too High
P249E Mercedes-Benz Code - Closed Loop Reductant Injection Control At Limit - Flow Too High

Common Causes of P249E Mercedes-Benz

  1. Faulty reductant injection control module
  2. Defective reductant flow control valve
  3. Wiring issues or electrical faults in the reductant injection system
  4. Malfunctioning reductant level sensor
  5. Contaminated or low-quality reductant fluid

Symptoms of P249E Mercedes-Benz

  1. Check Engine Light: The most common symptom associated with the P249E code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Engine Performance: The vehicle may experience reduced engine power or responsiveness due to the malfunctioning reductant injection control system.
  3. Increased Fuel Consumption: High reductant flow can lead to increased fuel consumption as the engine compensates for the incorrect emission control.
  4. Failed Emissions Test: If the P249E code is not addressed, it may result in the vehicle failing emissions tests due to excessive NOx emissions.

How to Fix P249E Mercedes-Benz

  1. Diagnose the Code: Use an OBD-II scanner to retrieve the P249E code and perform a thorough inspection of the reductant injection system components.
  2. Check reductant fluid quality: Ensure that the reductant fluid is of the correct type and quality, as contaminated or low-quality fluid can trigger the P249E code.
  3. Inspect wiring and connectors: Check the wiring harness and connectors for any signs of damage, corrosion, or loose connections that could affect the reductant injection control system's operation.
  4. Test reductant flow control valve: Test the reductant flow control valve for proper operation and replace it if it is found to be faulty.
  5. Reset the system: Clear the fault codes using the OBD-II scanner and reset the system to see if the P249E code reoccurs.

Cost to Fix P249E Mercedes-Benz

The typical repair costs for addressing the P249E code on a Mercedes-Benz vehicle can range from $200 to $500, depending on the specific cause of the issue and the parts and labor required for the repair. It is important to note that diagnosis time and labor rates at auto repair shops can vary significantly based on factors such as location, vehicle make and model, and the expertise of the technicians. It is advisable to consult with a trusted auto repair shop for a more accurate cost estimate based on the specific circumstances of the vehicle in question.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P249E Mercedes-Benz Code

1. What are the common symptoms of OBDII code P249E in a Mercedes-Benz?

The common symptoms of code P249E include the check engine light illuminating, reduced engine power, and potential exhaust system issues.

2. What can cause the OBDII code P249E in a Mercedes-Benz?

The code P249E is typically triggered by issues with the closed-loop reductant injection control system, often due to a malfunctioning reductant injector or a clogged reductant system.

3. How serious is the OBDII code P249E in a Mercedes-Benz?

Code P249E should be addressed promptly to prevent potential damage to the exhaust system and ensure optimal engine performance. Ignoring this code can lead to increased emissions and reduced fuel efficiency.

4. How can I diagnose the OBDII code P249E in my Mercedes-Benz?

Diagnosing code P249E involves using an OBDII scanner to retrieve the fault code, inspecting the reductant system components for any visible damage or leaks, and testing the reductant injector for proper function.

5. Can I continue driving my Mercedes-Benz with the OBDII code P249E present?

It is not recommended to drive your vehicle with the code P249E active, as it may lead to further complications and potential damage to the exhaust system. It is best to address the issue as soon as possible.

6. How can I repair the OBDII code P249E in my Mercedes-Benz?

Repairing code P249E may involve replacing the faulty reductant injector, clearing the fault code with a diagnostic tool, and performing a system reset to ensure proper operation.

7. Are there any preventive maintenance tips to avoid code P249E in a Mercedes-Benz?

Regularly servicing the reductant system, using high-quality diesel exhaust fluid (DEF), and keeping up with routine vehicle maintenance can help prevent issues that trigger code P249E.

8. Can a DIY enthusiast fix the OBDII code P249E issue in a Mercedes-Benz?

While some DIY enthusiasts may have the skills to address code P249E, it is recommended to consult a professional mechanic with experience in Mercedes-Benz vehicles to accurately diagnose and repair the problem.

9. How long does it take to fix the OBDII code P249E in a Mercedes-Benz?

The time required to fix code P249E can vary depending on the extent of the issue and the availability of replacement parts. In general, it may take a few hours to a full day to diagnose and repair the problem.

10. Is it expensive to repair the OBDII code P249E in a Mercedes-Benz?

The cost of repairing code P249E in a Mercedes-Benz can vary based on the root cause of the issue, the labor rates of the repair shop, and the cost of replacement parts. It is advisable to obtain multiple quotes from reputable mechanics for an accurate estimate.

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