OBD-II diagnostic trouble code
P0621Safe to drive

Generator Lamp Control Circuit Malfunction

The circuit controlling the dashboard charging warning lamp has a fault — a wiring issue with the warning light itself, not the charging system.

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Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.

Frequently asked questions

Can I drive with P0621?

In most cases, yes — P0621 is generally not an urgent safety issue and the car is usually safe to drive for a while. Still, get it checked soon, since the underlying cause can affect fuel economy or emissions the longer it's left.

How much does it cost to fix P0621?

The cost varies too much by cause and vehicle to give a single figure here — a diagnosis will narrow it down.

What causes P0621?

AS
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief
Code names compiled from open SAE/ISO references; explanations and repair guidance are original editorial content
Last verified: 09 Jul 2026 · Our methodology