Mercedes-Benz M Class Common Problems and Solutions
Poor Idle and Power Loss
Problem:
The car has very poor idle, and you have noticed a drop in power. The check engine light may come on with a P2006 code.
Solution:
The engine can't breathe thanks to non-moving flaps in the intake manifold. This is usually the result of damage to the actuator or the linkages. If you're lucky, installing a new actuator and replacing the linkages should resolve the issue. However, it may be that you have to order a new inlet manifold if the flaps have been damaged excessively. You can find all of the parts you need in the BreakerYard online store.
Difficulty level
Excessive Braking Distance
Problem:
Your brakes are no longer as effective at stopping the car.
Solution:
Driving a Mercedes is so smooth that it's easy to forget just how heavy they are. That weight means that you'll go through brake pads and brake discs far more often than on lighter cars. Check our parts page for the M Class to order four brake pads and four brake discs if they are worn or warped.
Difficulty level
Brake Pads
Engine Misfire (All Petrols)
Problem:
The engine has started to misfire regularly. If you check the oil, you can see metal shavings present.
Solution:
The timing chain on the M Class is a tough bit of kit, but it has been known to stretch in some cases. If that's happened to your car, then you need to replace it as quickly as possible. This is a fairly complex job, but it's worth doing yourself as a mechanic will charge an absolute fortune. We always have Mercedes timing chains available for quick delivery.
Difficulty level
Timing Chain
Excessive Engine Noise and Vibration
Problem:
The engine is extremely noisy when running, and you can feel a heavy vibration throughout the car.
Solution:
Have a look at your engine mounts. On the M-Class, it's fairly common for those to melt thanks to the engine running hotter than with previous generations. If you don't address this issue quickly, you will end up with additional problems such as broken belts and hoses. You can order a new engine mount directly from BreakerYard.
Difficulty level
Engine Mount
Water in Boot
Problem:
There is water inside your boot after rain or a carwash.
Solution:
This is extremely common on the M Class, and the water is getting into the boot via the right rear tail light seal. In most cases, you can apply some sealant to resolve this issue, although we do deliver Mercedes-approved replacement seals if you want to maintain your car's appearance.
Difficulty level
Knocking noise
Problem:
When you are driving, do you hearing a knocking noise coming from the centre console? If so, this is caused by the handbrake cable rubbing against the prop shaft.
Solution:
You will need to check the handbrake cable to ensure it has not been damaged by the rubbing. If it is ok, you can re-fit the cable otherwise you will need to fit a new one to resolve the issue.
Difficulty level
Wing Mirror failure
Problem:
The wing mirrors on the M-Class are prone to failure.
Solution:
If you are finding that one of the wing mirrors is not moving in all directions you will need to replace the whole mirror unit to fix the problem.
Difficulty level
Gear selector failure
Problem:
The M-Class is fitted with an American style gear selector which is located behind the steering wheel at the top of the steering column. This part is known for getting damaged and can be very costly if it is broken.
Solution:
If you are having problems with your gear selector and need to replace this part, we can help you find a replacement one at a very low price.
Difficulty level
Gear Selector
Rough idling/lack of power
Problem:
The EGR (Exhaust Gas Re-circulation) valves can get blocked up with a carbon build up. This results in rough idling and/or a lack of power when driving. You could also have black smoke coming from the exhaust and/or an oily smell in the cabin whilst driving. This issue results in too much exhaust smoke getting back to the engine, causing the issues mentioned above.
Solution:
You can remove the EGR valve and clean it out with a toothbrush and some sort of cleaner such as a carb cleaner. Watch the video below to see how to clean yours out:
Difficulty level
EGR Valve
Hot Seats
Problem:
Your seat heater is getting too hot for you to drive comfortably. In extreme cases, you may have noticed a burning smell.
Solution:
The heating elements inside the seat are prone to damage. You won't need to replace the individual heating elements, as we stock the improved heat pad design at a very low price.
Difficulty level
Loss Of Vehicle Control
Problem:
The car is drifting as you drive, leading to an increasing loss of control.
Solution:
It's likely that your front and/or rear axle bolts haven't been tightened sufficiently. That means they are very prone to cracks or splits. Order improved front and rear axle carrier bolts and tighten them securely into place.
Difficulty level
Deactivated Front Passenger Airbag
Problem:
Your front passenger airbag is deactivated so it won't deploy in a collision.
Solution:
Most M Class owners will have had this defect repaired already, so check your service history. If it hasn't been done, then a Mercedes dealership should update your software for free.
Difficulty level