Mercedes-Benz CLK problems, reliability and years to avoid
If you are considering buying a used Mercedes-Benz CLK, 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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Is the Mercedes-Benz CLK reliable?
The Mercedes-Benz CLK has 4 known faults in our database across 2 generations, 3 of them rated high severity. The most serious are engine (the timing chain sprocket on the balancer shaft of the M272 V6 in the CLK 280) and bodywork (rust is a serious problem on these cars, the same severe corrosion as other Mercedes). 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 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.
W208, 1997 to 2002
1 known fault, none rated high severity
W209, 2002 to 20093 high severity
3 known faults, the serious ones in the engine, bodywork
Years and engines with a serious known fault
2005 to 2008, M272 V6 petrol (CLK 280 and CLK 350): the timing chain sprocket on the balancer shaft of the M272 V6 in the CLK 280
1997 to 2009, All: rust is a serious problem on these cars, the same severe corrosion as other
2002 to 2013, 1.8 Kompressor / CGI Petrol (M271): single-row timing chain stretches and jumps teeth, destroying the valves
Each one is set out in full below, with the symptoms, the typical mileage and a rough repair cost.
Generation 1 of 21 known fault
Mercedes-Benz CLK W208 (1997 to 2002) problems
Engine/EmissionsMedium severity📝 Editorial
On the four-cylinder engines the seal of the camshaft adjuster magnet fails and oil creeps along the wiring loom into the ECU, lambda and other sensors, which then fail; left too long it can mean a new wiring loom. The archive lists it twice among the CLK's well known faults that can cause expensive damage, the second time as failing oil seals where the looms leave the top of the cam cover.
Rough guide
£150-1200, more if the loom or ECU has to be replaced
Typical symptoms
oil visible in the cam magnet connector or along the loom
sensor faults and engine warning light
rough running or poor economy from a contaminated lambda sensor
Affected vehicles
Engines:
Four-cylinder petrol (CLK 200, 200 Kompressor and 230 Kompressor)
Typical mileage:
60000-120000 miles
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Generation 2 of 23 known faults
Mercedes-Benz CLK W209 (2002 to 2009) problems
Engine/EmissionsHigh severity📝 Editorial
Single-row timing chain stretches and jumps teeth, destroying the valves
Rough guide
£1500-2500
Typical symptoms
loud metallic rattle on startup for 3-5 seconds
engine management light
loss of compression and non-start
Affected vehicles
Engines:
1.8 Kompressor / CGI Petrol (M271)
Typical mileage:
60000-90000 miles
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Engine/EmissionsHigh severity💬 3 owner reports, 2011 to 2017
The timing chain sprocket on the balancer shaft of the M272 V6 in the CLK 280 and CLK 350 wears prematurely, which Mercedes covered in a Star bulletin; it is a big engine-out job that the archive put at up to £4,000. A 2005 CLK 350's balancer shaft failed and cost £2,000 to replace, and a dealer-serviced 2007 CLK 280 showed an exhaust camshaft fault that the archive thought was possibly the same wear. The same fault is already recorded for the C-Class, E-Class, SLK and ML with this engine; this row carries it to the CLK.
Rough guide
£2000-4000
Typical symptoms
engine warning light with camshaft position or timing codes
rough idle or misfire
rattle from the front of the engine
Affected vehicles
Engines:
M272 V6 petrol (CLK 280 and CLK 350)
Typical mileage:
60000-90000 miles
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Bodywork/ChassisHigh severity💬 3 owner reports, 2013 to 2019
Rust is a serious problem on these cars, the same severe corrosion as other Mercedes of the period: a 2001 CLK 320 was scrapped after failing its MOT on five structural corrosion points, a 2003 car had all four wheel arches rusted with a £1,250 repair quote that Mercedes would not cover under its 30-year warranty, and a 2003 car's underside was thought to be corroded enough to fail an MOT and not be worth repairing. The archive's advice is not to buy a scruffy one unless it is thousands under book price.
Rough guide
£1250-3000, often more than the car is worth
Typical symptoms
bubbling along the wheel arch lips and sills
rust on the underside, subframe mounts and floor
MOT failure for structural corrosion
Affected vehicles
Engines:
All
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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 CLK advert and we check it in seconds.
Mercedes-Benz CLK timing chain, and service intervals
A timing chain has no change interval, which is not the same as lasting for ever. Listen for it on a used CLK, and check the oil has been changed on time. These are the figures UK specialists work to.
Automatic gearbox oil
722.6, 5G-TRONIC, 5 SPEED
40,000 miles
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.
Timing chainChain
M112, M113, 3.2 V6, 4.3 V8, 5.0 V8
No fixed replacement interval
Timing chain rather than a belt, with a deserved reputation for toughness: these engines regularly exceed 200,000-250,000 miles without internal rebuilds when oil changes are respected. No scheduled replacement. The known weak spot at high mileage is the chain tensioner, so listen for rattle on cold start. Covers the E320/CLK320-era M112 V6 and the 4.3/5.0/5.4 M113 V8s such as the E430 and S500.
Always confirm against the vehicle handbook. Intervals vary by engine, and several manufacturers revised theirs after failures in service.
Repair costs are typical UK ranges, not quotes. Actual cost depends on condition and garage.Data last verified: October 2026
Mercedes-Benz CLK buying questions
What are the most common Mercedes-Benz CLK problems?
Three stand out. Engine: the timing chain sprocket on the balancer shaft of the M272 V6 in the CLK 280 (typically 60000 to 90000 miles). Bodywork: rust is a serious problem on these cars, the same severe corrosion as other Mercedes of the period. Engine: single-row timing chain stretches and jumps teeth, destroying the valves (typically 60000 to 90000 miles). The full list above is grouped by generation, with typical mileage and a rough repair cost for each.
Which Mercedes-Benz CLK years should I avoid?
No Mercedes-Benz CLK year is a write-off, but the W209 (2002 to 2009) carries the most serious faults: engine and bodywork. The W208 (1997 to 2002) has none rated high severity. 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?
Ask the seller about the engine and bodywork faults on this page and whether they have been fixed, with invoices. On the test drive watch for engine warning light with camshaft position or timing codes, bubbling along the wheel arch lips and sills and loud metallic rattle on startup for 3-5 seconds. 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 CLK advert →
What is the real MPG of a Mercedes-Benz CLK?
Owners report 32.6 mpg on average across the Mercedes-Benz CLK engines with data, about 96% 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 209 owner submissions. Mercedes-Benz CLK Real MPG by engine →
Where this Mercedes-Benz CLK 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 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 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.