From Halopedia, the Halo wiki

The Coda was a small UNSC shuttle pod.


Captain Jacob Keyes took the Coda when he personally inspected the Pillar of Autumn when he assumed command of that vessel over Reach in 2552. During the inspection, R. Abiad was assigned to accompany Keyes in the inspection, in which they noticed several faults with the ship's M910 Rampart point defense network.[1] Keyes then docked the Coda in one of the Autumn's docking bays.[2] The pod probably was still aboard when the Autumn crashed on Installation 04 and was likely destroyed, either in the crash itself or during the destruction of Installation 04.