Engine-CodesMercedes-Benz – P0620 Mercedes-Benz

P0620 Mercedes-Benz Code - Generator Control Circuit Malfunction

Quick Answer

The P0620 code for Mercedes-Benz indicates a malfunction in the generator control circuit. Common causes include Faulty wiring in the generator control circuit, Malfunctioning generator, Defective voltage regulator. 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
P0620 Mercedes-Benz indicates Generator Control Circuit Malfunction.
Common causes
Common causes include Faulty wiring in the generator control circuit, Malfunctioning generator, Defective voltage regulator.
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.
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0620 Mercedes-Benz Description

The P0620 code for Mercedes-Benz indicates a malfunction in the generator control circuit. This circuit is responsible for managing the output of the vehicle's generator, which is essential for charging the battery and powering the electrical systems of the car. When this circuit malfunctions, it can lead to a variety of issues that can affect the overall performance of the vehicle.

OBDII Code P0620 Mercedes-Benz - Generator Control Circuit Malfunction
P0620 Mercedes-Benz Code - Generator Control Circuit Malfunction

Common Causes of P0620 Mercedes-Benz

  1. Faulty wiring in the generator control circuit
  2. Malfunctioning generator
  3. Defective voltage regulator
  4. Issues with the engine control module
  5. Loose or corroded connections in the circuit

Symptoms of P0620 Mercedes-Benz

  1. Check engine light illuminated
  2. Battery not charging properly
  3. Dimming or flickering lights
  4. Electrical system malfunctions
  5. Engine stalling

How to Fix P0620 Mercedes-Benz

  1. Diagnose the root cause of the issue by using a diagnostic scanner to read the fault codes and perform electrical testing.
  2. Inspect the wiring in the generator control circuit for any signs of damage or corrosion and repair or replace as needed.
  3. Test the generator and voltage regulator to ensure they are functioning correctly, replacing any faulty components.
  4. Clear the fault codes and reset the engine control module to see if the issue is resolved.
  5. Test the vehicle to ensure that the generator control circuit is now functioning properly and that the symptoms have been addressed.

Cost to Fix P0620 Mercedes-Benz

The typical repair costs for resolving a P0620 code on a Mercedes-Benz can range from $200 to $500, depending on the specific cause of the issue and the necessary repairs. This estimate includes parts and labor, but it's important to note that diagnostic time and labor rates can vary between auto repair shops. It's advisable to check with local shops for more accurate pricing information.

Tech Notes for P0620 Mercedes-Benz

Mercedes Benz Code = 0365 Operational fault of component (generator) (P0620)

When is the Code Detected?

The Engine Control Module (ECM) has fault detection circuitry which monitors the state of the generator turn on signal circuit. If the fault detection circuit senses a voltage other than what is expected, this P0620 code will set. The voltage regulator also contains fault detection circuitry. If the regulator detects a problem, the regulator will ground the generator turn on signal circuit, pulling the voltage low. This also causes the ECM to set the P0620 code.

Need more information about the P0620 Mercedes-Benz code?

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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 P0620 Mercedes-Benz Code

1. What are the common symptoms of OBDII code P0620 in a Mercedes-Benz?

- Common symptoms include issues with generator charging, illuminated battery warning light, dimming lights, and potential stalling.

2. What can cause the OBDII code P0620 in a Mercedes-Benz?

- The code P0620 is typically triggered by a malfunction in the generator control circuit, which can be caused by a faulty generator, damaged wiring, or a failing generator control module.

3. How serious is the OBDII code P0620 in a Mercedes-Benz?

- The code P0620 should be addressed promptly as it can lead to charging system malfunctions, battery drain, and ultimately, vehicle stalling or failure to start.

4. How can I diagnose the OBDII code P0620 in my Mercedes-Benz?

- Diagnosis of code P0620 involves using a diagnostic scanner to retrieve the specific fault code, testing the generator output, and inspecting the control circuit components for any visible damage.

5. Can I drive my Mercedes-Benz with the OBDII code P0620?

- It is not recommended to continue driving your vehicle with code P0620, as it can lead to unpredictable electrical system behavior and potential breakdowns.

6. What is the typical repair process for the OBDII code P0620 in a Mercedes-Benz?

- The repair process usually involves inspecting and repairing any damaged wiring, replacing a faulty generator or control module, and clearing the fault code from the vehicle's memory.

7. How much does it cost to fix the OBDII code P0620 in a Mercedes-Benz?

- The cost of fixing code P0620 can vary depending on the extent of the issue, replacement parts needed, and labor costs. It is advisable to consult a professional mechanic for an accurate estimate.

8. Can a DIY enthusiast fix the OBDII code P0620 in a Mercedes-Benz?

- While some DIYers with experience in automotive repair may be able to address code P0620, it is recommended to seek assistance from a qualified mechanic due to the complexities involved in the electrical system.

9. Are there any preventive measures to avoid the OBDII code P0620 in a Mercedes-Benz?

- Regular maintenance, such as checking the battery, charging system, and electrical connections, can help prevent issues that may lead to code P0620 in a Mercedes-Benz.

10. How long does it take to repair the OBDII code P0620 in a Mercedes-Benz?

- The repair time for code P0620 can vary depending on the exact cause of the issue, availability of parts, and the skill level of the mechanic. It is advisable to consult with a professional for a more accurate timeframe.

Discuss the causes and fixes for P0620 Mercedes-Benz OBDII Code

  • Alternator battery light goes on, I replaced battery and alternator but problem still exist. Any help or comment

  • Error message Po620 battery/charge light on. Battery and alternator replaced but problem still exists

  • Hello Edward. What model and year is your Mercedes Benz?

  • I'm having the same problem. Replaced voltage regulator replaced (was putting out 16.5V, and causing several other problem, battery was also going dead overnight). Everything is fixed except warning light still comes on. Voltage now 14.2-14.4.

  • What model and year is your Mercedes-Benz?

  • 2003 c230K

  • How long it takes for the light to come back? Replacing the regulator should have take care of the problem. There is a factory service bulletin that could help you inspect the regulator and alternator: https://goo.gl/J6ThHM

  • It doesn't seem consistent, but usually within the first 30s to 1min. I'll check the bulletin. One other thing I should mention, which I went to the dealer ship regarding and didn't get a good answer, they just wanted to replace parts..

    The voltage regulator, which was listed as the replacement online was actually the wrong part. It was Bosch, and identical in every way, voltage output e.t.c.. but the plug insertion grooves were opposite. Since I couldn't return it I removed the grooves so the plug would fit (since I couldn't return it anyway). I don't doubt that that could be the issue, however, considering the voltage was high (16.5V), I would like to find out if that possibly killed a relay of fuse before replacing another voltage reg and still have the same issue.

    There are two prongs coming from the VR but the plug only uses one of them. The voltage coming from the plug (to the ECU) is also 14.2..

  • And thanks, helpful bulletin! Tells me I don't have two-way communication from ECU and VR, and if my output voltage is correct, maybe the other prong is for input voltage to control the VR?

  • Correct, that may be the cause of the engine light

  • Well, that wasn't it. The other prong is just a lower voltage and can't find a VR schematics for individual models. Think I going to have to purchase the actual VR and go from there. Thanks for the help!