KNOWN FAULTS · Mercedes-Benz

Known faults for the Mercedes-Benz SLK (R172).

2011–2016 · Petrol / Diesel

Sources are not verified in real time and no entry confirms that your car is affected.

4 known faults with sources

Engines: SLK 200 / 250 (M271 EVO) (Petrol) · SLK 250 CDI (OM651) (Diesel) · SLK 350 (Petrol) · SLK 55 AMG (M152, 5.5 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.

Engines: SLK 200 / 250 (M271 EVO) (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.

Engines: SLK 200 / 250 (M271 EVO) (Petrol) · SLK 250 CDI (OM651) (Diesel) · SLK 350 (Petrol) · SLK 55 AMG (M152, 5.5 V8) (Petrol)

Applies if: Only if fitted with the automatic gearbox described in the record.

9G-Tronic harsh shiftingAutomatic gearbox

Engine / equipment: 9G-Tronic automatic gearbox (725.0 and 725.1): C-Class W205 and W206, E W212 and W213, CLS, S W222 and W223, GLC, GLE, GLS, SL and SLC
Period mentioned: 2013–2026
Symptoms: Harsh or jerky shifts (especially 1st to 2nd and when cold), vibration, delayed shifts or limp mode; sometimes the gear will not engage from N to D. Codes P073E00 and P07B700.
Possible cause described: Mercedes acknowledges in a technical bulletin complaints of harsh shifts, shudder and limp mode with various causes. In the early years (2014–2016) it is usually software or adaptation rather than mechanical damage; in other cases the pressure sensor built into the gearbox control unit fails.
Check for the garage: Follow the Mercedes bulletin: reproduce the complaint, save the EEPROM, check the oil level, run the Xentry valve flush, update engine, gearbox and shift unit software and perform the standstill adaptation. If it persists, check the control unit.
Cost cited in the source: Software update and adaptation: the most common and cheapest fix; repairing or replacing the control unit costs considerably more (the sources give no comparable figures)A rough figure from the original database, not an up-to-date quote.

Engines: SLK 250 CDI (OM651) (Diesel)

Chain, injectors and coolant leaksTiming / injection

Engine / equipment: OM651 2.1/2.2 CDI (C 200/220/250 CDI, E 200/220/250, GLK, Vito, Sprinter)
Period mentioned: 2008 onwards
Symptoms: Chain rattle on a cold start; on early units, loud injector knocking; coolant loss from the plastic coolant manifold or the EGR cooler.
Possible cause described: Plastic chain guide and a hydraulic tensioner that loses pressure (the chain is at the rear). Early units used problematic piezo injectors that Mercedes replaced in a campaign.
Check for the garage: Listen to a cold start, check the dealer's injector campaign history and check the coolant level.
Cost cited in the source: Chain: approx. €1,500–3,000 (estimate)A rough figure from the original database, not an up-to-date quote.