AutoCodes – Mercedes-Benz – P249E Mercedes-Benz

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

Quick Answer

Some manufacturers are now using a Diesel Exhaust Fluid (DEF) system commonly called a Selective Catalytic Reduction (SCR) system to reduce harmful Oxides of Nitrogen (NOx). Common causes include Exhaust Leaks, Fuel contamination, Faulty Diesel Particulate Filter (DPF). 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 Exhaust Leaks, Fuel contamination, Faulty Diesel Particulate Filter (DPF).
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 815

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 09, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P249E Mercedes-Benz Description

Some manufacturers are now using a Diesel Exhaust Fluid (DEF) system commonly called a Selective Catalytic Reduction (SCR) system to reduce harmful Oxides of Nitrogen (NOx). The diesel exhaust fluid is a Urea based solution of approximately 32% Urea and 64% distilled water. The solution is injected into the exhaust gas stream upstream of the SCR catalyst. Once in the exhaust system it decomposes and becomes Ammonia (NH3) and Carbon dioxide (CO2). Within the catalyst, the NH3 and CO2 react with the Nox to create Oxygen (O2) and harmless Nitrogen (N2).
The system requires a storage tank for the diesel exhaust fluid, a pump with integrated level sensor, pressure sensor and fluid quality sensor, an injector fitted to the exhaust system, fluid heater and the catalyst. Sensors can also be fitted close to the SCR catalyst to monitor temperature during regeneration.
The system is closely monitored for correct operation as failure of the system will have a large impact on vehicle exhaust gas emissions of oxides of Nitrogen.

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

What does this mean?

What are the Possible Causes of the DTC P249E Mercedes-Benz?

Exhaust Leaks
Fuel contamination
Faulty Diesel Particulate Filter (DPF)
Faulty NOx Sensor
Diesel Exhaust Fluid
Faulty Selective Catalyst Reduction (SCR) Catalyst

How to Fix the DTC P249E Mercedes-Benz?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P249E Mercedes-Benz code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P249E Mercedes-Benz code?

Need more information on how to fix the P249E Mercedes-Benz code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P249E Mercedes-Benz code diagnosed by a professional: Find a repair shop in your area

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.