What causes a P2504 code?

P2504 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a P2504 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P2504 active.

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBDIY

OBD-II

P2504

High Charging System Voltage (P2504)

What it means

The Engine Control Module (ECM) has detected that the battery charging voltage is exceeding the maximum calibrated threshold, usually above 15.5 or 16 volts.