IBST family
IBST_a031_decoupleBitTestFault
Power braking assist reduced
What does the IBST_a031_decoupleBitTestFault alert mean?
iBooster (IBST) detected a failure in system Application-Specific Integrated Circuit (ASIC). Failure is due to an electric or hydraulic decouple bit not being reset automatically.
What you'll see in your Tesla
- Power braking assist reduced
- Braking may require increased effort
What triggers it
IBST detects an ASIC failure due to an electric or hydraulic decouple bit automatic reset error.
When it clears
iBooster can not recover from this condition. iBooster replacement may be required.
Potential impact
IBST may not operate as expected.
Affected models
Cybertruck
Model 3 2017-2023
Model 3 2024+
Model S 2021+
Model X 2021+
Model Y
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.