P0561 — System Voltage Unstable

P0561: System Voltage Unstable — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

System Voltage Unstable. Basic catalogue definition; diagnostic details have not yet been reviewed.

Affected system: Powertrain

Symptoms

  • Flickering lights; difficult starting and erratic electronics.

Possible causes

  • Loose terminals, faulty regulator, weak battery or damaged wiring.

What to check

  • Test battery and charging; inspect terminals, cables and grounds.

Also written as: P0561-00, P056100, PO561 (some scan tools add the fault-type byte, e.g. -00).