2. Depress the brake pedal at least 5 times with the engine off, then start the engine with the pedal depressed. The pedal should feel like it's going down. In this case, the brake booster works normally. If this does not happen, check the tightness.
3. Otherwise, remove the vacuum hose on the brake booster, start the engine. Place your finger on the end of the hose and check for vacuum with the engine running.
4. If there is no vacuum: Check 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 a finger to see if there is a vacuum at the fitting.
6. If vacuum is applied: Measure low pressure value, replace brake booster if necessary (performed in the workshop).
Attention! When doing so, always replace the non-return valve in the vacuum line, as the diaphragm in the brake booster can be damaged by penetrating fuel vapours (with a faulty non-return valve).