What Is the P0620 Code?
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Seriousness
Can I Still Drive?
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The definition of code P0620 is “Generator Control Circuit,” sometimes also labeled as “Generator Control Circuit Malfunction.” This code indicates that the powertrain control module (PCM) or engine control module (ECM) has detected some kind of malfunction in the electrical signals from the vehicle’s generator control circuit. You may see DTC P0620 in many engine types as a generic powertrain code.
More About Error Code P0620
Vehicles maintain a generator on board that the PCM controls with a turn-off signal circuit. Whenever it needs to pull energy from the generator, such as to manage battery charge, it puts a five-volt signal through the turn-on signal circuit to the voltage regulator, which can control the generator output. However, if that generator turn-on signal circuit doesn’t respond as expected or returns an abnormal voltage, your vehicle will likely log code P0620. This issue can occur with a generator or alternator; while they are sometimes used interchangeably, a generator traditionally produces direct current or DC voltage, while an alternator first creates alternating current or AC voltage, then changes it to DC voltage.
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What Are the Symptoms of a P0620 Code?
The common symptoms of code P0620 can vary widely but will generally manifest as overall engine drivability issues. This may include engine stall when idling, delayed engine cranking, especially during a cold start, and, in some cases, the engine completely refuses to start. However, in other cases, the symptoms may not include any extremely noticeable symptoms, and you may primarily only see the check engine light turn on.
What Are Some Causes of a P0620 Code?
There are many possible common causes of the P0620 code. Some of these have to do with an actual malfunction, while others may just be an issue you can resolve. Here are a few:
- Battery failure or other issue with the automotive battery
- Faulty voltage regulator
- Poor electrical connection to the generator circuit
- An issue with the fault detection circuitry
- Controller programming error
- PCM programming error
Not all of these are equally likely. For example, a faulty PCM is much less likely than issues with your battery voltages. However, whether it’s your battery terminals, wiring for the alternator control circuit, or something else, you must get early help for the problem.
How Serious Is the P0620 Code?
You should consider the P0620 code to be extremely serious. Diagnostic trouble codes concerning power to your vehicle can cause significant problems. Even if you’re not dealing with driveability concerns right now, that doesn’t mean you’ll always be free of drivability issues. Your vehicle can become stuck in a no-start condition overnight, leaving you stranded. This fault code is important to fix soon, so it’s a good idea to pursue an exact diagnosis from a qualified source.
Can I Still Drive with a P0620 Code?
In many cases, you will physically be able to drive with the P0620 code active. It’s very uncommon for it to result in severe enough drivability issues that you have to avoid driving. However, that doesn’t mean it’s safe to drive when this code is active. This code means that you no longer have a reliable vehicle. It could develop starting and driving issues at just about any moment. You should take it in for a fix instead of continuing to drive with this code.
How Easy Is It to Diagnose a P0620 Code?
Diagnosis for a P0620 code can be difficult because of the little information from this code. This code happens due to a failed internal controller self-test, which sometimes may require multiple failure cycles to send the error code. General controller replacement may not fix it, which means you will need to know which parts of the vehicle to test and how to test them. If you don’t know how to narrow down the issues associated with these generic codes, it’s a good idea to talk to an expert.
How Difficult Is It to Inspect a P0620 Code?
As with diagnosis, inspection of the P0620 code will often be surprisingly difficult. Of course, you’ll need your OBD-II scanner, but you may also need other pieces of information, such as a diagnostic flow chart, wiring diagrams, and technical service bulletins, all of which can help guide you to the core problem when you may not have been able to do so otherwise. If you don’t have access to these tools, which most DIYers don’t, it could be a better option to talk to an experienced mechanic.
Need Additional Help with Your P0620 Code?
Most DIYers will not be equipped to handle the P0620 code on their own, even with their scan tool and other at-home tool options. That’s why it’s a good idea to get expert assistance when you can.
You’ll want to find an auto repair shop in your area. Because driving with the P0620 code is not recommended, finding a nearby auto repair shop will help you get the care you need without having to drive too far.
It’s also a good idea to check for other codes, as this will help you understand where the core problem is. The OBD-II database is a great starting point for this, as it will give you information about any additional codes you’re experiencing.
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