Problems with the pneumatic system can cause closing assist and door lock issues.
2004 Mercedes-Benz S500 Problem Reports
Most Reported 2004 Mercedes-Benz S500 Problem Reports
The door for the vanity mirror (or the frame for the door) can break; due to a redesign, the mirror "cassette" will need replacement.
The relay which turns the airmatic suspension pump on may fail causing the pump to run continuously. This can result in failure of the pump motor or a dead battery as the pump motor will continue to run after the car is turned off. Also, Worn airmatic pump mount bushings can causes noises in the front axle while driving on bumpy roads or a buzzing noise while the pump is running.
CD changers, command units, voice control units, PSE units, and Tele Aid units are prone to failure, especially in early models.
The crankshaft position sensor may fail. Symptoms of this are: The engine will crank—but not start—especially when the engine is warm. The car may start again if it is left to cool off, but it may run roughly or have poor performance.
The center console armrest can break. Replacement is commonly the recommended repair.
The brakes may begin to squeak at about the 50 percent wear point. This is due to the size and material used for the brake pads and rotors. The brake rotor surfaces become uneven, causing a lip to form at the outer edge. This will generally require replacement of the rotors when the pads are worn (pad life varies depending on driving style and terrain).
Leaks may develop from the differential cover and/or seals on high mileage or older vehicles. Our technicians recommend a complete reseal of the differential unit if these leaks are addressed.
Front thrust arm and control arm bushings can crack and sometimes tear completely. If this is not repaired quickly, damage to the front subframe unit will occur, which is very expensive to repair. Updated control arms (that prevent damage to the subframe when the bushings wear out) are available.
As brake fluid becomes dirty over time, it can cause a failure of the anti-lock brake system (ABS) modulator assembly. Our technicians recommend a complete brake system flush every two years to help prevent this issue.
The active body control system can leak fluid from numerous areas, including the tandem pump, hydraulic lines, struts, and/or seals. If it is not repaired, the vehicle ride height could drop too low and cause damage to the undercarriage.
The evaporator temperature sensor can fail, causing the AC compressor not to cycle. If the AC compressor does not turn on, the AC system will not blow cold air. If the compressor is stuck on, the air will be very cold at first, before warming up.
A door control module/actuator may fail. Our technicians recommend finding an expert to repair them. Taking the door trim panels off requires expert knowledge because they can break and the pieces are very expensive.
Due to exposure to the sun, lenses for head lights may become opaque (cloudy or hazy). This reduces the effectiveness of the lights. Our technicians tell us plastic polishes can improve the clarity of the lenses, but replacement of the lamp housings is the only way to regain the full intensity of the lights.