2. Press the brake pedal at least 5 times with the engine off, then start the engine with the pedal pressed. The pedal should noticeably go down. In this case, the brake booster works normally. If this does not happen, check for leaks.
3. Otherwise, remove the vacuum hose on the brake booster, start the engine, put your finger on the end of the hose and check for vacuum with the engine running.
4. If there is no vacuum: Check the vacuum hose for leaks and damage, replace if necessary. Tighten all hose clamps.
5. Diesel engine: Remove the hose from the vacuum pump and check with your finger if there is vacuum at the nipple.
6. If vacuum is applied: Measure low pressure value, replace brake booster if necessary (is done in the workshop).
Caution! Always replace the check valve in the vacuum line, as the diaphragm in the brake booster can be damaged by penetrating fuel vapors (if the check valve is faulty).