Mercedes-Benz CLK-Class problems, reliability and years to avoid
If you are considering buying a used Mercedes-Benz CLK-Class, these are the common problems worth knowing about first. Our garage database tracks 7 known faults for this model, 2 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 CLK-Class reliable?
The Mercedes-Benz CLK-Class has 7 known faults in our database across 2 generations, 2 of them rated high severity. The most serious are engine (soft metal on the timing chain sprocket that drives the balance shaft on the M272 V6) and gearbox (on automatic CLKs built from 2000 to 2003 with a Valeo radiator). 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 CLK-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.
1997 to 20021 high severity
6 known faults, the serious ones in the gearbox
2002 to 20091 high severity
1 known fault, the serious ones in the engine
Years and engines with a serious known fault
2004 to 2008, V6 petrol (M272: C 230/280/350, E 280/350, SLK 280/300/350, ML 350) / V8 petrol (M273: E 500 from 2006 and ML 500 from the 2008 model year; not fitted to the SLK, whose SLK 55 AMG uses the M113): soft metal on the timing chain sprocket that drives the balance shaft
2000 to 2003, Automatic gearbox with a Valeo radiator: on automatic CLKs built from 2000 to 2003 with a Valeo radiator
Each one is set out in full below, with the symptoms, the typical mileage and a rough repair cost.
Generation 1 of 26 known faults · 3 good notes
Mercedes-Benz CLK-Class (1997 to 2002) problems
ElectricalMedium severity📝 Editorial
The mechanism of the single-arm wiper requires frequent greasing and is not typically included in normal Mercedes service schedules. Failure can lead to an expensive replacement.
Rough guide
£800
Typical symptoms
Wiper arm slowing down or sticking
Wiper not moving smoothly across the windscreen
Wiper mechanism making unusual noises
Affected vehicles
Engines:
All
Typical mileage:
Unknown miles
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Bodywork/ChassisMedium severity📝 Editorial
Rust is a serious problem on the first CLK (1997 to 2002), as on other Mercedes of the time, and one 2001 CLK 320 was scrapped after failing its MOT on five structural corrosion points. Two owners of 2003 second-generation cars also reported it: one had severe corrosion underneath, thought not worth repairing, and the other had rust in every wheel arch, quoted at £1,250 and refused under the 30-year warranty.
Rough guide
£1250
Typical symptoms
bubbling paint around the wheel arches
corrosion on the underside and sills
MOT failure for structural rust
Affected vehicles
Engines:
All engines
Typical mileage:
unknown miles
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Transmission/ClutchHigh severity📝 Editorial
On automatic CLKs built from 2000 to 2003 with a Valeo radiator, the gearbox oil cooler inside the radiator can fail and let coolant into the transmission, wrecking it, with bills of £4,000 or more. For the second-generation car the models listed as affected are 209.365, 209.375, 209.376, 209.465 and 209.475.
Rough guide
£4000
Typical symptoms
harsh, slipping or erratic gear changes
coolant level dropping with no sign of a leak
milky or discoloured gearbox fluid
Affected vehicles
Engines:
Automatic gearbox with a Valeo radiator
Typical mileage:
unknown miles
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Engine/EmissionsMedium severity📝 Editorial
A faulty batch of manifolds went on to CLK 200 Kompressor engines built around 2000 and 2001. In time they crack, and a replacement is very expensive.
Typical symptoms
visible crack in the manifold
hissing or blowing noise from the engine bay
Affected vehicles
Engines:
CLK 200 Kompressor petrol
Typical mileage:
unknown miles
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ElectricalMedium severity📝 Editorial
On four-cylinder first-generation CLKs, the seal on the camshaft adjuster magnet at the top of the engine fails and oil creeps along the wiring loom, contaminating the engine ECU, the lambda sensors and other sensors. Caught late, it can mean a new wiring loom.
Typical symptoms
oil around or inside the plug on the camshaft magnet
engine management light and sensor faults
oil found in wiring plugs further along the loom
Affected vehicles
Engines:
Four-cylinder petrol engines
Typical mileage:
unknown miles
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Transmission/ClutchMedium severity📝 Editorial
On automatic CLKs of both generations, the oil seal where the wiring loom enters the electrically controlled gearbox is a recognised weak point. When it fails, oil escapes into the loom, which can lead to expensive damage.
Typical symptoms
oil around the gearbox electrical plug
oil weeping along the gearbox wiring
Affected vehicles
Engines:
Automatic gearbox
Typical mileage:
unknown miles
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What owners like
3 notes
The CLK model demonstrated strong reliability, placing eighth in a 2005 survey with only 15 repair claims per 100 vehicles.
This model had a very low death rate from accidents, scoring 2 out of 9 points.
Mercedes-Benz vehicles up to ten years old showed low average repair expenses in a 2002 warranty claims index.
Generation 2 of 21 known fault · 5 owner reports · 2 good notes
Mercedes-Benz CLK-Class (2002 to 2009) problems
Engine/EmissionsHigh severity📝 Editorial
Soft metal on the timing chain sprocket that drives the balance shaft on the M272 V6 (and the matching idler gear on the M273 V8) wears away, the camshaft timing drifts and eventually the engine timing is destroyed. It was covered by a manufacturer technical bulletin. One owner paid 2,000 pounds for a balance shaft on a 2005 CLK 350, and another car needed a timing repair and then a balance shaft within months.
Rough guide
£2000-4000
Typical symptoms
Engine Management Light (EML) on
fault codes P0016 / P0017 (camshaft timing)
rough running or misfiring
Affected vehicles
Engines:
V6 petrol (M272: C 230/280/350, E 280/350, SLK 280/300/350, ML 350) / V8 petrol (M273: E 500 from 2006 and ML 500 from the 2008 model year; not fitted to the SLK, whose SLK 55 AMG uses the M113)
Typical mileage:
60000-90000 miles
2 more owner reports back this up
August 2017The balancer shaft of the engine failed on a 2005 Mercedes-Benz CLK350, with replacement costing £2,000.
August 2015A 2007 Mercedes-Benz CLK 280, always serviced by Mercedes, showed an exhaust cam fault, possibly due to premature timing chain sprocket wear.
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What owners report
5 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.
Engine · February 2018An oil leak was reported from the engine of a 2005 Mercedes-Benz CLK 320CDI.
Suspension and steering · January 2016A 2007 CLK 320CDI with 57,000 miles experienced several issues, including power steering failure, a broken rear spring, and an oil leak.
Gearbox and clutch · November 2014The automatic transmission sump pan of a 2008 Mercedes CLK 280 failed due to corrosion.
Engine · February 2012At 200,000 miles, a CLK's valves may not seat correctly, requiring modified valve springs at a cost of £1,900.
Interior · May 2011Badly frayed front seatbelts on a five-year-old CLK were reported, sufficient to cause an MoT failure.
What owners like
2 notes
The car performs well, handles capably, and provides a comfortable driving experience.
The Mercedes-Benz CLK-Class is widely appreciated for its attractive and stylish exterior design.
Sellers rarely admit these faults outright
We track 18 specific phrases sellers use in adverts to soft-pedal these exact issues. Paste any Mercedes-Benz CLK-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: November 2026
Mercedes-Benz CLK-Class buying questions
What are the most common Mercedes-Benz CLK-Class problems?
Three stand out. Engine: soft metal on the timing chain sprocket that drives the balance shaft on the M272 V6 (typically 60000 to 90000 miles). Gearbox: on automatic CLKs built from 2000 to 2003 with a Valeo radiator. Bodywork: rust is a serious problem on the first CLK (1997 to 2002), as on other Mercedes of the time. The full list above is grouped by generation, with typical mileage and a rough repair cost for each.
Which Mercedes-Benz CLK-Class years should I avoid?
No Mercedes-Benz CLK-Class year is a write-off, but the Mercedes-Benz CLK-Class (2002 to 2009) carries the most serious faults: engine. The Mercedes-Benz CLK-Class (1997 to 2002) has high-severity faults on record too. 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 CLK-Class?
Ask the seller about the engine, gearbox and bodywork faults on this page and whether they have been fixed, with invoices. On the test drive watch for engine Management Light (EML) on, harsh, slipping or erratic gear changes and bubbling paint around the wheel arches. Read the MOT history for repeat advisories, then paste the advert into the free check, which reads it against all 7 known faults before you travel. Check a Mercedes-Benz CLK-Class advert →
What is the real MPG of a Mercedes-Benz CLK-Class?
Owners report 32.7 mpg on average across the Mercedes-Benz CLK-Class engines with data, about 95% 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 184 owner submissions. Mercedes-Benz CLK-Class Real MPG by engine →
Where this Mercedes-Benz CLK-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 CLK-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 CLK-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.