2003 Mercedes-Benz C240 4MATIC Problems

RepairPal has identified the most common problems with the 2003 Mercedes-Benz C240 4MATIC as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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Known Problems

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. Communicating these specific symptoms to your technician can save diagnostic time.

Catalytic converter failure is common and may cause a Check Engine Light to illuminate.

Bad spark plug wires can cause misfires; the Check Engine Light may illuminate.

The mass air flow (MAF) sensor tends to fail. The engine air filter should be replaced when the mass air flow sensor is replaced; a dirty filter can allow debris to damage the new sensor.

A dead battery can be caused by a faulty seat control module that does not properly shut down.  Spilling liquids on the front seats can cause these modules to fail.

The SRS (airbag) light can come on if liquids are spilled into the seat belt buckles, or if the liquid pools underneath the seat and gets into the electrical connector for the seat belt pretensioner. Damaged components will require replacement to restore proper airbag operation.

The heating, ventilation and AC (HVAC) heater box is susceptible to mildew buildup. This can result in a musty odor from the HVAC system, most noticeable when the system is first turned on.

The hold down nut for the upper front strut area can become loose, causing a knocking noise. This can be repaired without removing the strut assembly.

An engine Oil leak may develop from the PCV vent housing on the valve cover and/or the inspection plate on the front of the engine.

High mileage or older vehicles commonly develop leaks from the differential seals and/or cover. Our technicians recommend a complete reseal of the differential unit whenever these leaks are repaired.

A vibration felt through the center floor of the vehicle can be caused by driveshaft flex discs, which crack and shred, causing excessive driveshaft movement. Not repairing these can cause damage to the driveshaft center support bearing, or, in the worst case scenario, damage to the transmission or differential.

It is not uncommon to encounter premature failure of the anti-lock brake system (ABS) modulator assembly due to dirty brake fluid. Our technicians recommend flushing the brake fluid every two years in order to help prevent this problem.

Due to the size and material used on the brakes of these vehicles, the brakes may start to squeak around the 50 percent wear point. The brake rotor surfaces become uneven, causing a lip to form at the outer edge of the rotor. Because of this, the rotors are usually replaced when the pads are worn (pad life varies depending on driving style and terrain).

The sway bar end link joints may wear and cause a knocking noise over bumps. Loose or warn links should be replaced to correct this type of noise.