2005 Mercedes-Benz C320 Problems

RepairPal has identified the most common problems with the 2005 Mercedes-Benz C320 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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24
Known Problems

Mercedes Benz C230 models manufactured between 2005 and 2009 may have engine oil seeping or leaking from the back of the cylinder heads. This is commonly misdiagnosed as leaking valve covers.

On the back of the cylinder heads there are three, in total, plastic expansion plugs that plug access ports to the camshafts. These plugs are well known for seeping oil, and leaking if left unattended. The oil will run down the back of the engine and eventually make it to the ground. 

Replacement of these three plastic plugs is extremely simple, and should be done as regular maintenance. The recommended interval for replacement is every 60,000 miles.

The engine may develop a stalling and/or no start condition due to a failed crankshaft position sensor.

A repetitive clicking noise from behind the center area of the dash panel is usually caused by a broken stepper motor actuating arm. The actuating arm controls the direction of air flow in the climate control system. Disassembly of the center console will be required to access and change the broken arm with the updated, reinforced part.

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.

The electrical connector at the automatic transmission may leak fluid. Over time leaking fluid could migrate through the wiring harness and damage the transmission control module. If that happens a new harness and control module may be necessary to correct the problem.

Inside grab handles, the upholstery on the center console cover, and door trim panels can delaminate. Most commonly replacement of the affected part is necessary.

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.

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.

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.

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.