The engine computer is seeing lower voltage on the electrical system than it needs to run everything reliably. This isn't a code about one specific sensor — it's the computer flagging that the whole car's electrical supply is weaker than it should be.
Symptoms
- Dim headlights or interior lights, especially at idle
- Slow or difficult engine cranking
- Various warning lights coming on together, sometimes inconsistently
- Electronics (radio, windows, infotainment) behaving oddly or resetting
Likely causes
- A weak or failing battery that can no longer hold or deliver a proper charge
- A failing alternator not charging the battery sufficiently while driving
- Corroded or loose battery terminals/ground straps reducing the effective connection
- A worn or slipping alternator drive belt
How to diagnose it
- Test battery voltage at rest and while cranking with a multimeter — a healthy battery should read around 12.4-12.7V at rest
- Test alternator output voltage with the engine running (typically should be roughly 13.5-14.5V)
- Check all battery terminals and ground connections for corrosion or looseness
Typical fixes & cost
- Replace the battery100–250 EUR
- Replace the alternator250–700 EUR
- Clean/tighten terminals or replace a worn drive belt20–150 EUR
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.
AS
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief