P0560: Honda ECM backup supply loses voltage

P0560 has a broad system-voltage meaning, but Honda's cited implementation specifically monitors the ECM backup-memory power supply. This supply preserves stored data, including trouble codes and freeze-frame information, when the ignition is switched off.

Two supplies distinguish the fault

The documented criterion is backup voltage at or below 6.0 V for at least two seconds while the ECM's switched supply is at least 10.5 V after startup. That comparison is more specific than saying the entire battery voltage is low. The controller can have adequate operating power while its separate memory-retention supply is deficient.

Honda explains that an open or short in the backup supply can erase memory when ignition is turned off. Loss of stored diagnostic information is therefore relevant evidence in this implementation, not merely an inconvenience unrelated to the code.

Do not infer a charging-system repair automatically

The monitor description does not identify a universal alternator, battery or ECM replacement. The actual vehicle procedure must distinguish the backup feed and its connections from the switched feed. Record available data before cycling power or clearing memory, since the very circuit under investigation supports retention.

This variant runs continuously under its enable conditions and can illuminate the MIL in one qualifying drive cycle. After correcting the demonstrated supply fault, verify both the backup-voltage behavior and retention through the applicable ignition cycle. A healthy voltage reading at the battery alone does not establish that the ECM's backup terminal receives reliable power.

Source and applicability

Honda Advanced Diagnostics monitor collection, exact named monitor variant; the compiled document does not establish that every code applies to every Honda model/year. The manufacturer service document is available through a public mirror. Its diagnostic instructions take precedence over a general code dictionary.