OBD-II code · Network
U01B3 Lost Communication With Brake Blending Actuator
ECU lost communication with the brake blending actuator (modulates between regen and friction braking on hybrids/EVs).
Is it safe to drive with U01B3?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyActuator unpowered or wiring broken
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–8 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Brake Blending Actuator, Can Bus
Related codes
- U01B0Lost Communication With Battery Monitor Module
- U01B1Lost Communication With Particulate Matter Sensor B
- U01B2Lost Communication With Planetary Gear Set Control Module
- U01B4Lost Communication With Brake System Control Module B
- U01B5Lost Communication With Catalyst Heater Control Module
- U01B6Lost Communication With Fuel Heater Control Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.