AutoCodes – Mercedes-Benz – P0622 Mercedes-Benz

P0622 Mercedes-Benz Code - Generator Field 'F' Control Circuit Malfunction

Quick Answer

The Engine Control Module (ECM) uses the generator turn on signal circuit to control the generator. Common causes include Battery charge, Faulty Generator, Generator harness is open or shorted. 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: P0622 Mercedes-Benz indicates Generator Field 'F' Control Circuit Malfunction.
Common causes: Common causes include Battery charge, Faulty Generator, Generator harness is open or shorted.
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 4,345

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 01, 2019

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0622 Mercedes-Benz Description

The Engine Control Module (ECM) uses the generator turn on signal circuit to control the generator. A high side driver within the ECM allows the ECM to turn the generator ON and OFF. When Generator operation is desired, the ECM sends a 5 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the ECM, the voltage regulator controls generator output independently of the ECM. Under certain operating conditions, the ECM can turn Off the generator by turning Off the 5 volt signal on the generator turn on signal circuit.

OBDII Code P0622 Mercedes-Benz - Generator Field 'F' Control Circuit Malfunction - AutoCodes.com — P0622 Mercedes-Benz Code - Generator Field 'F' Control Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0622 Mercedes-Benz?

Battery charge
Faulty Generator
Generator harness is open or shorted
Generator circuit poor electrical connection
Engine Control Module (ECM) controlled generator
Faulty ECM

How to Fix the DTC P0622 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 does this mean?

Code Tech Notes

If the battery is OK then the alternator is more than likely the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0622 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 P0622 Mercedes-Benz code?

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Need Help with the 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 P0622 Mercedes-Benz Code

1. What does the OBDII code P0622 mean on a Mercedes-Benz?

P0622 indicates a malfunction in the Generator Field 'F' Control Circuit, which is responsible for regulating the alternator's output.

2. What are the common symptoms of code P0622 in a Mercedes-Benz?

Symptoms may include the battery warning light illuminating, difficulty starting the vehicle, dim headlights, or electrical accessories not functioning properly.

3. What causes the P0622 code to appear in a Mercedes-Benz?

Common causes include a faulty alternator, damaged wiring or connections in the generator control circuit, a defective voltage regulator, or issues with the PCM (Powertrain Control Module).

4. Can I drive my Mercedes-Benz with the P0622 code?

Driving with this code is not recommended, as it can lead to battery drain and potential vehicle shutdown due to insufficient charging of the electrical system.

5. How do I diagnose the P0622 code in my Mercedes-Benz?

Start by inspecting the alternator, wiring, and connectors for damage or corrosion. Test the alternator output and use a scan tool to check for related faults in the charging system.

6. How do I fix the P0622 code on a Mercedes-Benz?

Repairs may involve replacing the alternator or voltage regulator, repairing damaged wiring, cleaning corroded connections, or addressing PCM-related issues if necessary.

7. How much does it cost to fix the P0622 code on a Mercedes-Benz?

Costs vary depending on the specific issue, but alternator replacement typically ranges from $500 to $1,000, including parts and labor.

8. Can a bad battery cause the P0622 code in a Mercedes-Benz?

While a bad battery itself is not a direct cause, it can exacerbate charging system issues and should be tested as part of the diagnostic process.

9. Does the P0622 code always mean the alternator is bad?

No, the code could also be triggered by faulty wiring, a defective voltage regulator, or issues with the PCM, so a thorough diagnosis is essential.

10. Can I reset the P0622 code without fixing the issue in my Mercedes-Benz?

Clearing the code without addressing the underlying problem may temporarily turn off the warning light, but the issue will likely return and could lead to further damage.