AutoCodes – Buick – P0620 Buick

P0620 Buick Code - Generator 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 Voltage Regulator, Faulty Generator. 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 Buick indicates Generator Control Circuit Malfunction.
Common causes: Common causes include Battery charge, Faulty Voltage Regulator, Faulty Generator.
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 8,384

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
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0620 Buick 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 P0620 Buick - Generator Control Circuit Malfunction - AutoCodes.com — P0620 Buick Code - Generator Control Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0620 Buick?

Battery charge
Faulty Voltage Regulator
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 P0620 Buick?

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 P0620 Buick 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 P0620 Buick 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.