Checking the assistive device

Press the brake pedal several times, when the engine is not running, to remove residual vacuum from the servo.
Keep the brake pedal depressed and start the engine.
A perceptible drop of the pedal shows that the power of the servo has been generated and the servo is efficient. If the pedal does not drop, this damage should be sought in a leaky connection of the vacuum hose, in the check valve or in the booster.
To replace a damaged vacuum line, Disassemble its stubs at the supporting device and at the vacuum pump (applies to the engine 1,6 D) or disconnect from the intake manifold (applies to engines 1,2 and 1,3). Replacement cables are only supplied with a woven cover and therefore must be fixed with cable ties after installation.

The above instructions also apply to replacing the check valve. The arrow on the valve body must point towards the suction tube. All cable connection points must be completely airtight.

Finally, check the operation of the booster.