[mlyle]

Well, that's an interesting thing. During taxi-in, the cabin altitude should be the ground altitude; outflow valves open at touchdown.

Hard to understand how an an incipient failure could manifest then (e.g. from increased leakage).

Of course, there's warning lights for excessive cabin pressure, etc, too... which would point to a different theory of the problem than a structural manufacturing problem.

[I_Am_Nous]

Is "sensor just no longer responding" a failure mode which could trigger the alarm?