Which gauge reading would indicate a failure in the SCU?

An illuminated OIL PX annunciator serves as a warning indication that the oil pressure in the system is outside of normal limits, which is a key indicator of potential issues with the SCU (System Control Unit). The SCU is responsible for various engine and system functions, including the lubrication system. If the oil pressure is insufficient or too high, it could indicate a failure in the SCU or related components, leading to potential engine performance issues.

In contrast, high oil pressure does not specifically indicate a SCU failure, as it can occur for several reasons. A constant N1 measurement might suggest normal engine operation within a certain range, and a stable ITT reading generally implies the engine is operating properly. These conditions do not directly point to a malfunction of the SCU, making the illuminated OIL PX annunciators the most telling sign of a fault.