U01B3
- Network & Communication
- Generic (SAE)
- Safety
Stop driving
Continuing to drive risks injury or major mechanical damage. Shut the engine off when it is safe to do so.
Lost Communication With Brake Blending Actuator
This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.
ECU lost communication with the brake blending actuator (modulates between regen and friction braking on hybrids/EVs).
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Continuing to drive risks injury or major mechanical damage. Shut the engine off when it is safe to do so.
- Urgency
- Stop driving
- Will it pass emissions
- Not affected
- Check engine light
- Solid
- Clearing the light
- A completed drive cycle is normally required before the monitor re-runs and the light can clear.
- 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
Many vehicles show no symptom at all beyond the warning light. The absence of a symptom does not mean the fault is not real.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Actuator unpowered or wiring broken | Very common | — |
| 2 | Gateway module routing CAN messages incorrectly | Occasional | — |
| 3 | CAN terminating resistor (120 Ω) drifted out of spec | Occasional | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
- Brake Blending Actuator
- CAN Bus
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Awaiting review
Found something wrong? Tell us — we publish corrections.