KNOWN FAULTS · Mercedes-Benz

Known faults for the Mercedes-Benz GL / GLS (X166).

2012–2019 · Diesel / Petrol

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

4 known faults with sources

Engines: GL 350 BlueTEC / GLS 350 d (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.

Engines: GL 350 BlueTEC / GLS 350 d (OM642) (Diesel) · GL 500 / GLS 500 (Petrol) · GL 63 / GLS 63 AMG (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: GL 350 BlueTEC / GLS 350 d (OM642) (Diesel) · GL 500 / GLS 500 (Petrol) · GL 63 / GLS 63 AMG (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: GL 350 BlueTEC / GLS 350 d (OM642) (Diesel) · GL 500 / GLS 500 (Petrol) · GL 63 / GLS 63 AMG (5.5 V8) (Petrol)

Applies if: Only if fitted with air suspension.

AIRMATIC leaks and compressorSuspension

Engine / equipment: AIRMATIC air suspension: E-Class W211, W212 and W213, S W220 to W223, CLS, CL, ML W164, GL, GLE and GLS
Period mentioned: 2002–2026
Symptoms: One corner sags overnight, suspension fault warning, the compressor runs a lot or a compressor overheated message appears; eventually the car sits low and rides hard.
Possible cause described: The air bellows on the struts leak with age, often at the upper crimp rings, and the compressor overworks until it burns out. The valve block and lines also leak, and the compressor relay (in the rear SAM on W221, W222 and W213) and ride height sensors fail.
Check for the garage: Spray soapy water on bellows, lines and valve block; read each corner's data with Xentry; check the compressor fuse and relay. Do not replace the compressor without fixing the leak first, or the new one will fail soon.
Cost cited in the source: Compressor: approx. €600–1,200 at an independent garage (converted from Canadian dollars); bellows: depends on the cornerA rough figure from the original database, not an up-to-date quote.

Mileage cited in the database: 95,000–115,000 km. This is not a maintenance interval and does not predict a failure.