Quick question on how critical warnings would be stored on a Mercury ECM. Are they stored by date/time stamp? Or stored by hours/run time?

Example: A low oil pressure warning happens, the warning is cleared, is that warning stored in the ECM by the date/time that it happened? Or is it stored by run time? Or both? Being that this is considered a critical warning would it not have triggered Guardian Mode?

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Posted by Hog Zealot

On the Flats

Member since Mar 2012

1763 posts

Posted on 1/15/26 at 12:30 pm to YOURADHERE

Critical warnings in a Mercury ECM, such as a low oil pressure event, are typically stored as logged faults with associated engine data snapshots. These include details like the engine hours/run time at the time of occurrence, RPM ranges, and other parameters (e.g., temperature, pressure) captured during the fault. There is no indication of calendar date/time stamps being used, as outboard ECMs generally lack a real-time clock and rely on operational metrics like run time for logging.

The low oil pressure warning would remain stored in the ECM as a logged fault even after being cleared or acknowledged (e.g., via reset or resolution of the issue). This allows for diagnostic review using tools like a scan tool or SmartCraft system, which can access active and historical faults along with occurrence counts and engine data at the fault time.

Low oil pressure is considered a critical condition and would trigger Engine Guardian Mode, which activates a warning horn (typically a continuous beep) and reduces engine power/RPM to protect against damage. Guardian Mode engages automatically for issues like insufficient oil pressure, and power is restored only after the throttle is returned to idle and the fault is no longer detected; if it persists, the limitation remains until addressed.

I put your question in Grok and it spit that out.