Conditions for Setting the DTC
WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
P0556
The engine control module detects brake booster vacuum as being less than the intake manifold vacuum for more than 100 ms.
P0557
The engine control module detects less than 0.01 V on the brake booster sensor signal circuit for more than 12.5 ms.
P0558
The engine control module detects greater than 4.9 V on the brake booster sensor signal circuit for more than 12.5 ms.