P0620 Code: Generator Control Circuit Malfunction
🟠 Moderate severity · drivable
Drivable short-term, but the alternator isn't being controlled properly, so the battery may not charge.
What P0620 means
The alternator's control circuit has an electrical fault, so the computer can't regulate charging. The battery may not charge properly, leading to a dead battery.
Symptoms
- Check engine light is on
- Battery or charging warning light
- Dim headlights
- Battery going dead
Common causes
- most common: Failing alternator
- common: Damaged wiring or loose connector at the alternator
- less common: Faulty engine control module
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Test the alternator and replace it if failing | Mechanic | $200–500 |
| Repair damaged alternator wiring | Mechanic | $50–150 |
Frequently asked questions
Can I drive with a P0620 code?
Short distances, yes, but the battery may not charge and the car could die. Fix it soon.
What is the most common cause of P0620?
A failing alternator or damaged alternator wiring.
How much does it cost to fix a P0620?
Typically $200–$500 for a new alternator.
Related codes
P0562
P0562 Code: System Voltage Low
P0560P0560 Code: System Voltage Malfunction
P0622P0622 Code: Generator Field/F Terminal Circuit
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.