Table of contents: Do-it-yourself steering repair? ↓ Airbag: repair only in a workshop ↓
The power steering, which is fitted as standard in the A4, makes the driver's work of turning the steering wheels considerably easier. It ensures maximum comfort when manoeuvring and also gives the driver a good "feel" for the steering on high-speed motorways.
The force needed to support the driver's efforts is provided by the hydraulic system. This system consists of a pump driven by the engine's poly-V belt, a fluid reservoir, and hydraulic lines.
The principle of the system: The pump sucks oil from the tank and delivers it under high pressure to the valve body, which is located in the steering mechanism. Depending on the steering wheel turn, oil is delivered to the left or right side of the working cylinder. There, the oil presses on the piston of the rack mechanism and thus maintains the movement of the steering mechanism.
Leaving aside some adjustment and maintenance work, it can be said that you cannot do power steering maintenance yourself, especially repair it. Most often, you have to check the oil level in the reservoir.
Power steering: 1 - tie rod end, 2 - hex nut 40 Nm. 3 - band clamp (must be replaced), 4 - cuff (after setting the toe-in, the cuff should not be twisted), 5 - sealing ring round section (must be replaced), 6 - Power steering (lubricate the toothed rack with steering gear grease A0F 000 05), 7 - hose clamp (must be replaced), 8 - transverse steering rod.
Do-it-yourself steering repair?
Power steering repair is a workshop job. Workshops have special test devices that allow you to interrogate the control unit codes, and the staff has the appropriate knowledge. This is the only way to avoid electronic component failures and the damage that can be caused by these failures, as well as high repair costs. Therefore, power steering repair should be left to a workshop. If repaired unqualifiedly, the steering may fail.
Airbag: repair only in a workshop
Strict regulations must be followed even when transporting and storing airbags, the same applies to work stations intended for dismantling and installing the airbag module. In addition, the gas generator, which immediately inflates the airbag in the event of a collision, is subject to the Explosives Act. Therefore, the manufacturer allows only trained personnel to install airbags in series; in workshops, this work is carried out by qualified specialists. For this reason, we strongly recommend that you refrain from any work related to the steering wheel with an airbag, as well as the front passenger airbag. This also applies to cosmetic repairs, when, for example, the steering wheel is additionally equipped with a wooden or leather trim. Airbags should only be handled by workshops.
(This publication is borrowed from the resource AudiManual)