P0620 Code: Generator Control Circuit Malfunction

On-board diagnostic trouble codes are meant to help drivers and/or mechanics diagnose vehicle problems. In order to identify what has caused them to be logged, you must first find out what the retrieved code means.

Did your scan tool retrieve a P0620 code? This generic trouble code points to a possible problem in your vehicle’s generator control circuit. Learn more about it through this article.

What Does the P0620 Code Mean?

Diagnostic trouble code (DTC) P0620 stands for “Generator Control Circuit Malfunction.”

The powertrain control module (PCM) energizes and monitors the generator control circuit as you drive your vehicle. Each time you switch the ignition on, internal self-tests are done. The PCM uses the controller area network (CAN) to monitor and compare signals from each individual module. It does this to ensure that the controllers are communicating with each other properly.

Once the PCM detects a problem as it monitors signals from the generator control circuit, it will trigger the P0620 code. It’s important to note that driving with this trouble code isn’t recommended. Bring your vehicle to the nearest shop right away for proper diagnosis.

Note: The definition of code P0620 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What Are the Common Causes of the P0620 Code?

• Open or shorted wirings (general control circuit)
• Bad alternator/generator assembly
• Insufficient control module ground
• PCM programming error

What Are the Common Symptoms of the P0620 Code?

• Battery/charging light illuminated
• Drivability problems
• Engine might stall when idling
• Delayed engine cranking

How to Diagnose the P0620 Code

The P0620 is a generic code that can be seen across several makes and models. However, this does not mean there’s one diagnostic procedure that will work for all vehicles. The steps for diagnosing this code will vary depending on your vehicle’s specifications.

Check out this video to get an idea of what the diagnostic process for this code might involve:

How to Fix the P050D Code

The symptoms of code P0620 can be similar across several types of vehicles. However, that does not mean that there’s one solution that will work for all makes and models. Make sure to refer to a factory repair guide that is specific to your car.

If you’d like to troubleshoot this code on your own, make sure to consult a vehicle-specific repair manual or an online repair database. These resources contain the appropriate diagnostic and repair procedures for this code. If you’re not an experienced automotive DIYer, we strongly suggest leaving the job to a trusted professional.