Alongside the HTC-made handset are an altitude and orbit control system, two propulsion setups and a Linux-based computer with a "high-speed" processor.
Steady electronic "heartbeat" tones relayed from Curiosity across space to Earth indicated a successful landing to the control room at Jet Propulsion Laboratory.
The problem came to light when a Propulsion Drive Electronics (PDE) control unit picked up a difference in pressures between the oxidiser and the fuel going through one of the ATV's four "propulsion chains".