ABS hydraulic units provide the pressure your car needs to prevent its wheels from locking.
Your cars ABS hydraulic unit receives commands from the ABS controller. This in turn obtains
speed-related data from sensor rings on each wheel. When the sensor ring detects that one of your wheels
is spinning at a different speed than the others, the controller tells the ABS hydraulic unit to close
the solenoid valve. This then reduces the braking force on the offending wheel and stops it from locking
for more than a nanosecond. A faulty ABS hydraulic unit could cause your car to fail its MOT. If your
wheels are locking and you see a warning light appear on the dashboard, it could be that your ABS
hydraulic unit is not working as it should.