KNOWN FAULTS · Mercedes-Benz
Known faults for the Mercedes-Benz CLK (W209).
2002–2009 · Petrol / Diesel
Sources are not verified in real time and no entry confirms that your car is affected.
Buying it used?Which engine has the fewest documented faults, which recalls to ask the seller about and what to look for on the test drive.Before you buy
6 known faults with sources
Engines: CLK 200 Kompressor (M271) (Petrol) · CLK 220 / 270 CDI (Diesel) · CLK 320 CDI (OM642) (Diesel) · CLK 280 / 350 / 500 (Petrol) · CLK 55 AMG (5.4 V8) (Petrol) · CLK 63 AMG (6.2 V8) (Petrol)
Applies if: Only if fitted with 7G-Tronic. Confirm the gearbox type.
7G-Tronic conductor plateGearbox
- Engine / equipment
- 7G-Tronic automatic gearbox (722.9) in the C, E, S-Class, ML, GL, SLK, Sprinter…
- Period mentioned
- 2004 onwards (more failures in 2004–2008)
- Symptoms
- Gearbox stuck in 2nd or 3rd (limp mode), harsh shifts, delay engaging D or R, gearbox warning often without an engine light; turning off and restarting clears it for a while.
- Possible cause described
- The conductor plate (the control unit with built-in speed sensors) fails from heat and vibration. Oil leaks through the 13-pin connector are also common.
- Check for the garage
- Diagnose with Xentry/STAR to see the sub-codes (a basic reader only shows P0700). Check for oil in the gearbox connector.
- Cost cited in the source
- Approx. €1,400–2,800 (estimate)A rough figure from the original database, not an up-to-date quote.
Sources from the original database
Go-Parts: P0700 on an E-Class with 722.9ECU Testing: 7G-Tronic failureMercedes Medic: placa conductora 722.9
View full entryEngines: CLK 200 Kompressor (M271) (Petrol)
M271 chain and camshaft adjustersTiming system
- Engine / equipment
- M271 1.8 Kompressor / CGI (C 180/200 W203 and W204, E 200 W211/W212, CLK 200, SLK 200)
- Period mentioned
- 2002–2015
- Symptoms
- Rattle for 2–3 seconds or more on a cold start; engine light for camshaft timing deviation.
- Possible cause described
- A single-row chain that stretches and cast-iron camshaft adjusters whose teeth wear. On later versions the hydraulic tensioner fails more often.
- Check for the garage
- Listen to a cold start, read timing fault codes and check the chain replacement history.
- Cost cited in the source
- €1,500–3,000A rough figure from the original database, not an up-to-date quote.
Sources from the original database
Autoscore: M271 1.8 KompressorAustralian Car Reviews: M271 cam adjustersMBClub UK: M271 chain and sprocketsAu7o: Mercedes SLK with M271
View full entryEngines: CLK 200 Kompressor (M271) (Petrol) · CLK 220 / 270 CDI (Diesel) · CLK 320 CDI (OM642) (Diesel) · CLK 280 / 350 / 500 (Petrol) · CLK 55 AMG (5.4 V8) (Petrol) · CLK 63 AMG (6.2 V8) (Petrol)
Applies if: Only if fitted with the automatic gearbox described in the record.
13-pin connector leak on the 722.6 gearboxAutomatic gearbox
- Engine / equipment
- 722.6 five-speed automatic (5G-Tronic), not the 7G-Tronic: C-Class W203, E-Class W210 and W211, CLK, S-Class W220, ML W163, SLK, SL R230, Vito and Sprinter with this gearbox
- Period mentioned
- 1996–2013
- Symptoms
- Oil around the electrical connector on the side of the gearbox, harsh shifts or slipping, delayed engagement and limp mode: the car stays in one gear (usually 2nd and reverse after a restart) and the engine light comes on.
- Possible cause described
- The plastic adapter of the 13-pin connector has O-rings that harden and let oil out. Oil can wick up inside the wiring to the gearbox control unit and damage it. If the problem persists after replacing the connector, there may be oil in the harness, a damaged wire or a conductor plate fault.
- Check for the garage
- Read the gearbox control unit codes before switching off if possible (a restart can clear them). Look for oil at the connector and, with it unplugged, on its pins and at the control unit plug. According to the service bulletin, the connector should only be removed with gearbox oil below 50 °C to avoid damaging the conductor plate, and the harness must be routed without tension.
- Cost cited in the source
- Connector adapter: about $15–20 in parts (US prices quoted in the sources), plus the lost fluid; labour extra. If oil has reached the control unit, the repair is bigger.A rough figure from the original database, not an up-to-date quote.
Sources from the original database
Brake & Front End (ALLDATA): oil leak at the 722.6 connectorMercedesMedic: replacing the 722.6 13-pin connectorMercedesMedic: P0715 and P0720 codes and limp modeMBClub UK (forum): oil in the 722.6 harness on an ML55Bob Is The Oil Guy (forum): CLK320 in limp modeThe Transmission Shop: leaks and limp mode in Mercedes gearboxes
View full entryEngines: CLK 320 CDI (OM642) (Diesel)
Oil cooler and injector leaksOil leaks / injectors
- Engine / equipment
- OM642 3.0 V6 CDI/BlueTEC (280/300/320/350 CDI, ML, GL, R, Sprinter)
- Period mentioned
- 2005 onwards
- Symptoms
- Oil pooling in the engine's V, burning oil smell, drips under the engine; or a hiss or chirp next to an injector with an exhaust smell.
- Possible cause described
- The oil cooler seals (in the engine's V) degrade. Separately, injector washers leak combustion gas and carbon builds up around the injector.
- Check for the garage
- Visual inspection of the engine's V and the base of the injectors.
- Cost cited in the source
- Oil cooler seals: labour-heavy, approx. €800–1,800 (estimate)A rough figure from the original database, not an up-to-date quote.
Sources from the original database
View full entryEngines: CLK 280 / 350 / 500 (Petrol)
M272 / M273 balance shaft sprocketTiming system
- Engine / equipment
- M272 V6 (280, 300, 350) and M273 V8 (450, 500, 550) in the C, E, CLK, CLS, SLK, ML, GL, R, S and CL
- Period mentioned
- 2004–2008 (engines below serial number 2729..30 468993)
- Symptoms
- Engine light with P0016 and P0017 (1200 and 1208 on Mercedes diagnostics), rattle on start-up, hesitation, misfires and, in severe cases, stalling.
- Possible cause described
- Balance shaft sprocket (M272) or timing idler gear (M273) made from metal that is too soft: the teeth wear, the chain goes slack and the timing slips. Mercedes changed the material in mid-2008.
- Check for the garage
- Compare the engine serial number with the 2729..30 468993 cut-off, read cam correlation codes and, if in doubt, inspect the sprocket with a borescope. First rule out the cam adjuster magnet (a cheap fault).
- Cost cited in the source
- Engine-out repair: over €3,700 (converted from dollars)A rough figure from the original database, not an up-to-date quote.
Sources from the original database
Mercedes Medic: checking the balance shaft by VIN8020 Automotive: M272 balance shaft failureGo-Parts: P0017 on the M272Go-Parts: P0017 on the M273
View full entryEngines: CLK 63 AMG (6.2 V8) (Petrol)
AMG 6.2 (M156) head bolts and camshaftsEngine (cylinder head / valvetrain)
- Engine / equipment
- M156 6.2 V8 AMG (C 63 W204, E 63 W211 and W212 until 2011, CLK 63, CLS 63, ML 63, S 63 and CL 63 until 2010, SL 63)
- Period mentioned
- 2006–2015
- Symptoms
- Coolant loss, coolant in the oil or white smoke (broken head bolts); rattle or ticking on start-up (camshaft and lifter wear).
- Possible cause described
- Cylinder head bolts that break on engines up to 2012 (Mercedes bulletin from 2011) and nodular cast-iron camshafts that wear together with the lifters, mainly on the intake side (bulletin from 2009).
- Check for the garage
- Overnight cooling system pressure test, oil analysis and camshaft inspection with a borescope.
- Cost cited in the source
- Major engine repair (several thousand euros)A rough figure from the original database, not an up-to-date quote.
Sources from the original database
Australian Car Reviews: C 63 AMG faultsAustralian Car Reviews: M156 engineAustralian Car Reviews: CLS 63 and the bolt bulletinFCP Euro: M156 faults
View full entryEngines for this model
- CLK 200 Kompressor (M271)Petrol
- CLK 220 / 270 CDIDiesel
- CLK 320 CDI (OM642)Diesel
- CLK 280 / 350 / 500Petrol
- CLK 55 AMG (5.4 V8)Petrol
- CLK 63 AMG (6.2 V8)Petrol