AutoCodes – Mercedes-Benz – P20BF Mercedes-Benz

P20BF Mercedes-Benz Code - Reductant Heater 'B' Control Circuit Low

Quick Answer

The reductant heater and sender assembly contains pickup tube for reductant pump module, an electric heating element, a reductant temperature sensor and an electrode type level sensor. Common causes include Faulty Reductant Heater, Reductant Heater harness is open or shorted, Reductant Heater circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P20BF Mercedes-Benz indicates Reductant Heater 'B' Control Circuit Low.
Common causes: Common causes include Faulty Reductant Heater, Reductant Heater harness is open or shorted, Reductant Heater circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 4,081

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jul 29, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P20BF Mercedes-Benz Description

The reductant heater and sender assembly contains pickup tube for reductant pump module, an electric heating element, a reductant temperature sensor and an electrode type level sensor. The heating element is directly above pickup tubes inlet filter. When reductant temperature sensor detects the diesel exhaust fluid temperature dropping to the freezing point of 12°F (-11°C), the Powertrain Control Module (PCM) will command the glow plug control module to provide voltage to heating element. The heating element thaws liquid reductant within reductant heater and sender assembly reservoir during cold ambient temperatures.

OBDII Code P20BF Mercedes-Benz - Reductant Heater 'B' Control Circuit Low - AutoCodes.com — P20BF Mercedes-Benz Code - Reductant Heater 'B' Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P20BF Mercedes-Benz?

Faulty Reductant Heater
Reductant Heater harness is open or shorted
Reductant Heater circuit poor electrical connection

How to Fix the DTC P20BF 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 P20BF 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 P20BF Mercedes-Benz code?

Need more information on how to fix the P20BF Mercedes-Benz code? Get Access to Factory Service Manuals

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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 P20BF Mercedes-Benz Code

1. What does the OBDII code P20BF mean on a Mercedes-Benz?

P20BF indicates a problem with the Reductant Heater 'B' control circuit, specifically that the circuit is reading low voltage or is malfunctioning.

2. What are the symptoms of the P20BF code in a Mercedes-Benz?

Common symptoms include the check engine light turning on, poor engine performance, issues with the DEF (Diesel Exhaust Fluid) system, and potential reductions in fuel efficiency.

3. What causes the P20BF code to appear?

The code is typically caused by a malfunctioning reductant heater, damaged wiring or connectors, a blown fuse, or issues with the DEF system control module.

4. Can you drive a Mercedes-Benz with the P20BF code?

While the vehicle may still be drivable, prolonged operation with this issue can lead to emissions system malfunction and possible limp mode activation.

5. How is the P20BF code diagnosed?

A mechanic will use an OBDII scanner to verify the code, inspect the reductant heater and related wiring for damage or corrosion, and test the control circuit for proper voltage and resistance.

6. How do you fix the P20BF code on a Mercedes-Benz?

Repairs may include replacing the reductant heater, repairing or replacing damaged wiring or connectors, replacing a blown fuse, or reprogramming the DEF system control module.

7. Is the P20BF code covered under warranty for a Mercedes-Benz?

It depends on your vehicle's warranty coverage and age. Emissions-related components may be covered under federal or manufacturer-specific emissions warranties.

8. What is the purpose of the reductant heater in a Mercedes-Benz?

The reductant heater prevents DEF fluid from freezing in cold temperatures, ensuring proper operation of the Selective Catalytic Reduction (SCR) system.

9. How much does it cost to fix the P20BF code on a Mercedes-Benz?

The repair cost can range from $200 to $800, depending on whether the reductant heater, wiring, or other components need replacement.

10. Can a faulty reductant heater damage the engine?

A faulty reductant heater wonâ€™t damage the engine directly, but it can cause the SCR system to malfunction, leading to increased emissions and potential drivability issues.