If you are considering buying a used Mercedes-Benz M-Class, these are the common problems worth knowing about first. Our garage database tracks 4 known faults for this model, 3 of them rated high severity. Every one below is a repair bill a seller has good reason not to mention.
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Check a Mercedes-Benz M-Class advert (free) →The Mercedes-Benz M-Class has 4 known faults in our database across 3 generations, 3 of them rated high severity. The most serious are engine (oil cooler seals fail in the 'V' of the engine causing massive oil leaks) and engine (soft metal on the timing chain sprocket that drives the balance shaft on the M272 V6). None of them makes the car a bad buy on its own; the risk is a seller who knows and says nothing.
That is a count of the faults we hold, not a reliability score. Popular cars get written about more, and a newer generation has had less time to show its faults.
No year is a write-off on its own. What matters is which serious faults a given year and engine can have, and whether the car in front of you has had them fixed.
Each one is set out in full below, with the symptoms, the typical mileage and a rough repair cost.
One owner each, in their own words rewritten as a line, and not counted in our risk scoring. A fault joins the list above once a second report or an editorial source backs it.
Sellers rarely admit these faults outright
We track 12 specific phrases sellers use in adverts to soft-pedal these exact issues. Paste any Mercedes-Benz M-Class advert and we check it in seconds.
Check an advert now (free) →Recall work is done by the manufacturer, and GOV.UK says you will not usually have to pay for it. These are the 9 DVSA recalls for the M-Class, newest first. They do not tell you whether this particular car has had the work: for that, put the registration into the free GOV.UK MOT history check, which shows a recall status where the manufacturer shares it, or ask a franchised dealer to check the VIN.
The driver's airbag may have a chemical change to its propellant over time.
Put right by: Replace the drivers airbag.
The driver's airbag may have a chemical change to its propellant over time.
Put right by: Replace the drivers airbag
Where a control unit coding was updated in a workshop between 3 December 2016 and 5 December 2016 the coding may not correspond to the specification and may trigger unplanned action in the vehicle. The safety and emissions systems may not react as design intent.
Put right by: Recall the vehicles that are likely to be affected and update the software in the corresponding control units.
The ball joint securing the upper arm to the steering knuckle may not have been tightened to the correct torque.
Put right by: On affected vehicles check installation of upper arm and replace arm if necessary
The high-voltage battery charger may not have been produced to specification which could lead to an incorrect detection of an external charging cable. This in turn can lead the request for P to be activated. If the speed is less than 5 km/h the transmission would activate the park pawl function which will prevent the vehicle from driving further and could increase the risk of an incident.
Put right by: Recall the vehicles that are likely to be affected and replace the high-voltage charger on the affected vehicles.
On certain diesel engines the 'O' ring may not have been produced to the correct specification. This may allow oil to leak and contaminate the environment. If excessive oil is lost engine damage may occur.
Put right by: On affected vehicles replace the chain tensioner sealing ring.
If the vehicle is equipped with all weather or ribbed accessory mats it is possible that the mats may impede the operation of the throttle pedal to the extent that it could cause a delay in the throttle pedal returning when released.
Put right by: Recall all affected vehicles check and if fitted remove the accessory mats.
With the use of all weather or ribbed accessory floor mats temporary contract between the floor mat and accelerator pedal cannot be completely ruled out. In the event of contact between the floor mat and accelerator pedal the accelerator pedal may possibly be released with a delay.
Put right by: Check whether the vehicle is equipped with an all weather or ribbed accessory floor mat. If one of the affected floor mats is inserted in the driver footwell the floor mat must be removed from the vehicle so that the above complaint can no longer occur.
It has been established that if the vehicle is fitted with all weather or ribbed floor mats the accelerator/throttle pedal may contact the floor mat. Although this will just be a temporary contact this could delay the accelerator/throttle pedal releasing.
Put right by: Recall affected vehicles and check if the vehicle is fitted with all weather/ribbed floor mats. If fitted remove from the vehicle.
Recall data published by the Driver and Vehicle Standards Agency under the Open Government Licence v3.0. A recall listed here may not apply to every car of this model: the build dates and the registration check are what decide it.
A timing chain has no change interval, which is not the same as lasting for ever. Listen for it on a used M-Class, and check the oil has been changed on time. These are the figures UK specialists work to.
Generally robust, but can stretch at high mileages. The primary failure point on this engine is the oil cooler seals in the 'V', not the chain.
Officially 'sealed for life' but independent specialists recommend ATF (MB 236.14 spec, which supersedes 236.10 and 236.12) and filter changes every 40,000 miles to head off valve body and conductor plate trouble. Capacity is about 7.5 litres. Fitted to most pre-2011 rear-wheel-drive Mercedes including the pre-2010 C, E and SLK.
Always confirm against the vehicle handbook. Intervals vary by engine, and several manufacturers revised theirs after failures in service.
Three stand out. Engine: oil cooler seals fail in the 'V' of the engine causing massive oil leaks (typically 60000 to 100000 miles). Engine: soft metal on the timing chain sprocket that drives the balance shaft on the M272 V6 (typically 60000 to 90000 miles). Suspension: air suspension compressor failure, relay failure, or leaking air struts causing the car to collapse (typically 80000 to 120000 miles). The full list above is grouped by generation, with typical mileage and a rough repair cost for each.
No Mercedes-Benz M-Class year is a write-off, but the W164 (2005 to 2011) carries the most serious faults: engine and suspension. The W163 (1998 to 2005) and W166 (2011 to 2015) have none rated high severity. Year matters less than whether the specific car has had the known fixes, so check the history for them.
Ask the seller about the engine and suspension faults on this page and whether they have been fixed, with invoices. On the test drive watch for oil pooling in the engine valley, engine Management Light (EML) on and car sitting very low over the wheels. Read the MOT history for repeat advisories, then paste the advert into the free check, which reads it against all 4 known faults before you travel. Check a Mercedes-Benz M-Class advert →
The DVSA lists 9 safety recalls for the Mercedes-Benz M-Class issued between 2012 and 2021. The most recent, from August 2021, is "The driver's air bag may have a chemical change to its propellant over time". Recall work is done by the manufacturer, and GOV.UK says you will not usually have to pay for it. This list is by model, so it cannot tell you whether one particular car has had the work: the free GOV.UK MOT history check shows a recall status from the registration where the manufacturer shares it, and a franchised dealer can check the VIN.
Looking at a Mercedes-Benz M-Class right now? Check the advert before you go and see it.
If you used to check the Honest John “Good & Bad” section before the site closed in 2026, this page is where that information now lives. We rebuilt the Mercedes-Benz M-Class owner-report history from the archived Honest John dataset, added our own research, specialist and owner-club sources and DVSA recall data, and we keep it free. Each fault above is badged with its source. The same data feeds our free advert check, which reads a listing against every known fault for the exact engine and year.
CarAdCheck is not affiliated with Honest John or Volkswagen Financial Services. What happened to Honest John, and where each feature lives now.
Knowing what a Mercedes-Benz M-Class goes wrong with is half of it. The rest is reading the advert and checking the car's history before you hand any money over.