System voltage and charging
P0620
Generator Control Circuit
The car's electrical system voltage is too low or too high, or the alternator's control circuit has a fault.
Fix it soon
Can I keep driving? For a short while, gently. Have it checked in the next few days, and stop if the car feels, sounds or smells different. Low voltage can leave you stranded and can cause strange behavior in other systems. High voltage can damage electronics.
Common causes
- A failing alternator
- A worn or loose drive belt
- An old battery
- Corroded or loose battery cables
- A wiring fault
Listed roughly from most to least likely. The same code can have different causes on different cars.
What to do
- Have the battery and alternator tested. Most parts stores do it free.
- Check the battery terminals are clean and tight.
- Check the drive belt.
General guidance. Your owner's manual wins. If a red warning light is on or the car drives differently, stop safely and get help.
Related codes
Track this automatically in Tagwell Auto
Tagwell Auto keeps your car's service dates and mileage, so when a code shows up you know what was done last. With a Bluetooth reader for the car's diagnostic port (called OBD-II), the phone app can read the code itself.