Mercedes-Benz R-Class problems, reliability and years to avoid
If you are considering buying a used Mercedes-Benz R-Class, these are the common problems worth knowing about first. Our garage database tracks 2 known faults for this model, 1 of them rated high severity. Every one below is a repair bill a seller has good reason not to mention.
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Is the Mercedes-Benz R-Class reliable?
The Mercedes-Benz R-Class has 2 known faults in our database, 1 of them rated high severity. The most serious are engine (the R 350 petrol uses the M272 3.5 V6, one of the engines where the sprocket) and engine (r 280 CDI, R 320 CDI and R 350 CDI models have the OM642 3.0 V6 diesel). 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.
Which Mercedes-Benz R-Class years should you avoid?
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.
Years and engines with a serious known fault
2006 to 2008, R 350 petrol (3.5 V6, M272): the R 350 petrol uses the M272 3.5 V6, one of the engines where the sprocket
Each one is set out in full below, with the symptoms, the typical mileage and a rough repair cost.
Generation 1 of 12 known faults · 2 owner reports · 4 good notes
Mercedes-Benz R-Class W251 (2006 to 2013) problems
Engine/EmissionsMedium severity📝 Editorial
R 280 CDI, R 320 CDI and R 350 CDI models have the OM642 3.0 V6 diesel, whose oil cooler sits in the vee of the block on seals that go hard with age and heat. When they give up, oil gathers on top of the engine under the intake and can find its way down to the undertray.
Rough guide
£800-1500
Typical symptoms
oil pooled on top of the block beneath the intake
oily undertray or drips under the rear of the engine bay
burning smell once the engine is hot
Affected vehicles
Engines:
R 280 CDI / R 320 CDI / R 350 CDI (3.0 V6 diesel, OM642)
Typical mileage:
Unknown miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
Engine/EmissionsHigh severity📝 Editorial
The R 350 petrol uses the M272 3.5 V6, one of the engines where the sprocket on the balance shaft is made of metal too soft for the job. As its teeth wear, the camshaft timing slips out of step, the engine light comes on and, left alone, the timing gives way altogether.
Rough guide
£2000-4000
Typical symptoms
engine management light
camshaft position codes P0016 or P0017 stored
uneven idle or hesitation
Affected vehicles
Engines:
R 350 petrol (3.5 V6, M272)
Typical mileage:
Unknown miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
What owners report on the W251
2 single reports, unconfirmed
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.
Brakes · April 2016A 2011 R350 CDI experienced ABS and ESP warnings, then lost power with a choking sound from the front left brake shortly after purchase.
Engine · April 2013A 2008 R320 CDI with 58,000 miles developed a main crankshaft bearing issue despite having a full Mercedes service history.
What owners like about the W251
4 notes
This model offers a practical and spacious alternative to traditional people carriers.
The R-Class provides a very generous amount of interior space for occupants and luggage.
The R-Class was offered in a long wheelbase variant, providing significantly increased interior space for passengers and cargo.
From 2010, the R-Class was offered as a seven-seater, an increase from its original six-seat configuration.
Sellers rarely admit these faults outright
We track 6 specific phrases sellers use in adverts to soft-pedal these exact issues. Paste any Mercedes-Benz R-Class advert and we check it in seconds.
Repair costs are typical UK ranges, not quotes. Actual cost depends on condition and garage.Data last verified: September 2026
Mercedes-Benz R-Class buying questions
Which Mercedes-Benz R-Class years should I avoid?
No Mercedes-Benz R-Class year is a write-off, but the W251 (2006 to 2013) carries the most serious faults: engine. Year matters less than whether the specific car has had the known fixes, so check the history for them.
What should I check when viewing a used Mercedes-Benz R-Class?
Ask the seller about the engine faults on this page and whether they have been fixed, with invoices. On the test drive watch for engine management light and oil pooled on top of the block beneath the intake. Read the MOT history for repeat advisories, then paste the advert into the free check, which reads it against its known faults before you travel. Check a Mercedes-Benz R-Class advert →
What is the real MPG of a Mercedes-Benz R-Class?
Owners report 27.8 mpg on average across the Mercedes-Benz R-Class engines with data, about 91% of the official combined figure. The gap between official and real-world economy varies a lot by engine, so the Real MPG page lists every engine and generation separately, from 43 owner submissions. Mercedes-Benz R-Class Real MPG by engine →
Where this Mercedes-Benz R-Class fault data comes from
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 R-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.
Knowing what a Mercedes-Benz R-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.