MyTeslaMate
RCU family

RCU_a056_redundantControllerIsMaster

Power braking assist reduced

What does the RCU_a056_redundantControllerIsMaster alert mean?

The Redundant Control Unit (RCU) is the master hydraulic brake controller.

What you'll see in your Tesla

  • Power braking assist reduced
  • Braking may require increased effort

What triggers it

The IDB_boosterStatus signal has indicated that the Integrated Dynamic Brake (IDB) is unable to generate hydraulic brake pressure.

When it clears

The IDB_boosterStatus signal indicates that the Integrated Dynamic Brake (IDB) is now able to generate hydraulic brake pressure.

Potential impact

The Redundant Control Unit will provide brake boost when the driver applies the brake pedal. This will result higher than normal brake pedal forces being required to achieve a given vehicle deceleration in addition to vibrating noises when the pedal is pressed.

Affected models

Model Y 2025+

Track your Tesla's alerts automatically

Alerts like this reach MyTeslaMate through your car's Tesla telemetry API. MyTeslaMate logs every alert your Tesla reports and turns it into readable history and real-time notifications — hosted TeslaMate with no server to run.