Battery, charging and glow plugs

P0620 Fault in alternator control

By: Diagno editorial team · Updated: 2026-10-15

P0620 means: Fault in alternator control. The engine computer can't control the alternator properly. Drive gently and have the car checked soon. The repair usually costs about €80–500 in Estonia. The most common cause: alternator wire or connector. Other possible causes: voltage regulator, alternator has failed.

Is it safe to drive?Get it checked soonDrive gently and have the car checked soon.

Typical repair cost€80–500parts and labour in Estonia

What it means

The engine computer can't control the alternator properly. The battery may not be charging.

What could be wrong

1Alternator wire or connector
2Voltage regulator
3Alternator has failed

What you can check yourself

See whether the battery light is on in the dashboard. Measure battery voltage with the engine running. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

We measure charging
We check the wiring
We replace the regulator or alternator

Standard SAE description: Generator Control Circuit

This code usually comes with: Battery (charging) lightSee what the light means →Check the fuse · If a light, the horn, wipers, a socket or the fuel pump is dead, a blown fuse may be the cause.Fuse boxes by car →

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong. Repair price depends on the work involved, generally €45 per hour.

Book a diagnostic check

Questions

What does fault code P0620 mean?

Fault in alternator control. The engine computer can't control the alternator properly. The battery may not be charging.

Can I drive with code P0620?

Drive gently and have the car checked soon.

How much does it cost to fix P0620?

Roughly €80–500 in Estonia. The price depends on exactly what has failed and on the car.

How is P0620 fixed?

We measure charging. We check the wiring. We replace the regulator or alternator.

Based on AI combined with our hands-on workshop experience and knowledge. This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.