What it means
Brake blending system performance fault — coordination between regenerative and hydraulic braking degraded.
At a glance
- Usually lights the ABS or stability-control warning light
- The engine or gearbox may go into limp mode
How it works
The brake blending system coordinates regenerative braking from the drive motor with friction braking from the hydraulic brakes. This code sets when the control system detects that their combined response is outside expected performance, which may involve pressure, wheel-speed, motor-torque, wiring, or control inputs.
Common causes
Most likely first.
- Regenerative and hydraulic brake outputs not coordinating
- Fault in brake-blending control module or software
- Wheel-speed, brake-pressure, or motor-torque signal fault
- Wiring or connector fault
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Save freeze-frame data and compare live brake pressure, wheel-speed, motor-torque, and blending command data around the time the fault occurred.
- Inspect related connectors and wiring for damage, corrosion, loose terminals, or water entry.
- Check for other ABS, wheel-speed, brake-pressure, or powertrain codes that could identify a faulty blending input.
- Test any indicated wheel-speed or pressure sensor circuits and compare sensor readings with the manufacturer's specification.
- If the input signals and wiring pass, run the manufacturer's brake blending system tests and check for applicable control module setup or software requirements.
Common fixes
- Repair damaged wiring or poor connections affecting brake blending inputs.
- Repair or replace a faulty wheel-speed or brake-pressure sensor identified by testing.
- Correct a motor-torque signal fault if it is disrupting the regenerative braking input.
- Complete required brake blending module setup or software service when specified for the vehicle.
- Replace a control module only after its inputs, wiring, and setup have been verified.
Can I keep driving?
Regenerative and hydraulic braking may not coordinate normally, and ABS or stability control may be limited. Avoid high-speed driving; stop and arrange recovery if pedal feel or stopping performance changes.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.