Mercury – Dash-Mounted Catalyst Malfunction Light | Engine Alert Indicator | 8M0046481Mercury Dash Mounted Catalyst Malfunction Light Engine Alert Indicator 8M0046481 Overview Catalyst equipped MerCruiser engines rely on a clear visual alert when the emissions system needs attention. The Mercury 8M0046481 Dash Mounted Catalyst Malfunction Light gives you that reminder. When the catalyst system detects a fault, this light turns onmuch like the check engine light in a car or truckletting you know its time to get the engine inspected. Its