P2504
Charging System Voltage High
The ECU detects a battery voltage above the regulated upper limit. The voltage regulator is not limiting alternator output, risking damage to electronic modules and battery overcharge.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Faulty voltage regulatorCommon
- Poor alternator groundPossible
Parts involved
- Alternator
- Voltage Regulator
- Battery
P2504 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.