2009 Mercedes-Benz ML350 Problem Reports

RepairPal Verified 2009 Mercedes-Benz ML350 Problem Reports

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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.

It is not uncommon for the power steering rack to develop a fluid leak requiring replacement of the rack assembly. Loss of power steering fluid may also cause an abnormal noise and damage to the power steering pump.

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

The camshaft adjuster solenoid (which is related to the variable valve timing system) may fail or timing chain/balance shaft components may wear, resulting in illumination of the Check Engine Light and various drivability issues. Mercedes-Benz has released a service bulletin outlining specific repair instructions depending on fault codes stored.

The heater blower motor can become abnormally noisy. Replacement of the blower motor is commonly necessary to correct this concern.

On vehicles with airmatic suspension, the airmatic pump relay can stick, causing a dead battery, because the pump continues to operate when it should be shut off. Eventually, the pump will fail; the pump, fuse, and relay will need replacement. After parking and exiting the vehicle, the airmatic pump should only run for a few seconds before turning off. It should not come back on until the driver's door is opened.

After a heavy rain storm, the drains for the heating, ventilation and AC (HVAC) system intake can be plugged with leaves and other debris, causing a dead battery. Water fills the intake cavity and overflows into the vehicle, directly onto the blower motor and its regulator. This causes the regulator to short out and the blower motor will continue to run, despite the key being off and removed from the vehicle. Usually the carpet at the right front passenger floor will be wet too. If the carpet is saturated, the passenger seat may need to be removed to dry out the battery storage area before water or moisture reaches the relay and fuse holders. To prevent this, do not let leaves and twigs accumulate at base of windshield. If there are leaves or debris below the wiper blades, clean the area.

Motor mounts commonly fail, causing engine vibrations to be transferred to the body. Failed motor mounts should be replaced in order to prevent damage to the transmission mount.

As the spark plug wires age and are exposed to heat cycling, they start to develop micro cracks in the insulation around the resistors, which causes misfires and poor fuel economy.

Bolts that connect the automatic tailgate actuator lever to the tailgate can break. The broken bolts need to be drilled out and the holes re-threaded before a new bolt can be installed. If you hear any unusual noises when raising or lowering the power tailgate, have the mounting bolts inspected to make sure they are tight so the problem can be repaired before the bolts break.

 

 

The tailgate latch may stick causing a drain on the battery while the vehicle is parked.

A no start condition may develop due to an anti-theft system fault. If the drive authorization module fails to recognize the keys, the engine will not start. In many cases, a new module and keys will be needed to correct this problem.

Due to slipping clutches in the transfer case, a shudder or rumbling from the center of the vehicle may occur, especially when turning at slow speeds. If the clutches are not too badly worn, changing the fluid will fix this problem. Otherwise, the transfer case will need to be disassembled to change the clutches.

Vehicles equipped with a 7-speed automatic transmission may develop a rough shifting condition, most commonly going up from first to second gear and going down from third to second or second to first gear. Our technicians tell us this is due to an internal component failure. Mercedes has released updated parts; the transmission will need to be removed and disassembled to complete the necessary repairs.

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.