Outback F4-2.5L (2008)
2) Stop the engine and check the vacuum gauge.
If the vacuum pressure drop within 15 seconds after stopping the engine is 3.3 kPa (25 mmHg, 0.98 inHg) or less, the function of brake booster is
normal.
If defective, refer to "AIR TIGHTNESS CHECK".
3) If the brake booster is faulty, replace it with a new part.
^
Lack of boost action check
Turn the engine OFF, and set the value of the vacuum gauge to "0". Then, check the fluid pressure when the brake pedal is depressed. The pressure
must be greater than the specification listed.
^
Boosting action check
Set the vacuum gauge reading to 66.7 kPa (500 mmHg, 19.69 inHg) with the engine running. Then, check the fluid pressure when the brake pedal is
depressed. The pressure must be greater than the specification listed.