ML 320 CDI OM642, known issues
W164 · 2005–2011 · R4 High risk
Recorded issues7
Walk-away1
Over €1,0005
Checkable at viewing3/7
Likely spend€4,750
Likely spend is the mid cost of every issue rated common or universal, added together, what an unmaintained example owes over the next few years, not a prediction for any one car. Worst case if everything here failed at once is €15,200, which isn't a realistic scenario but is a useful ceiling.
All issues, by system
Engine
A camshaft position fault code, a rough or lumpy idle, and a check engine light that returns after clearing. Balance shaft gears on M272 engines built inside the early range wore prematurely against the crankshaft gear. Later engines used a revised gear, so the engine number decides the risk rather than the mileage or the service book.
Check: Take the engine number and check it against the affected range before you look at anything else, because no amount of service history answers this. A stored camshaft correlation code is the other warning.
Later parts: Revised balance shaft gear on later production engines
Oil weeping down the back of the block, burning smell, oil in the valley beneath the intake. The oil cooler sits in the vee under the intake manifold and its seals harden with age. Access requires the intake off, so labour dominates the bill.
Check: Look down the back of the engine with a torch for wet oil and fresh cleaning. A suspiciously spotless engine bay on a 200,000 km V6 deserves a question.
Suspension
The car sitting low after standing, a message on the dashboard, or a compressor that runs far longer than it should. The struts perish and leak, and the compressor then runs continuously until it burns out. Cars used for short trips and left standing suffer first, because the bags crack where they fold.
Check: View the car cold and before it's been started, then cycle every ride height and watch all four corners respond. A compressor that runs on after levelling is the early warning.
Emissions
Warning light, limp mode, oil level rising above the maximum mark from fuel dilution. The filter needs sustained hot running to regenerate. A car used for short urban trips never completes a regeneration cycle.
Check: Read the DPF soot load and the distance since the last regeneration on a scan tool, and check the engine oil level and smell it for diesel. Ask what the car was used for. A short-trip city diesel is the wrong car regardless of mileage.
Coolant loss with no visible external leak, white smoke, sweet smell. The EGR cooler cracks internally and leaks coolant into the intake. BMW recalled affected diesels over a fire risk from glycol deposits igniting.
Check: Check coolant level and look for unexplained top-ups in the service history. Verify the recall was carried out. It's free and searchable by VIN.
Transmission
7G-Tronic conductor plate and 13-pin connector leak (722.9)Mercedes 7G-Tronic seven-speed automatic (722.9)€400–€900
Harsh, delayed or jerky shifts, holding a gear then banging the next in, and limp mode, often with speed-sensor or gear-ratio fault codes. The speed sensors in the conductor plate (mechatronic) fail, and/or the external 13-pin connector leaks fluid that wicks up the wiring into the control unit. Early units are the most affected.
Check: Test-drive through every gear cold and warm. Scan the transmission, and pull the external 13-pin plug to check for fluid on the pins.
Turbo & intake
Limp mode and power loss, usually with fault code P2015 stored. The actuator motor that drives the intake-port shut-off flaps in the manifold fails, frequently after being shorted by oil dripping from the turbo-inlet seal above it; the flaps or linkage can also seize.
Check: Scan for P2015 and related intake codes; a car that has thrown it before is likely to again unless the oil-leak cause was addressed.
How to read this
Every issue is authored once against the part that actually carries it: the engine, the gearbox, the chassis or a shared component, and inherited by every variant that has that part. The badge next to each issue says where it comes from, so you can tell an OM642 problem from an E9x problem.
Evidence tiers. Manufacturer means a recall, technical bulletin or revised part number. Documented means workshop data or multiple independent sources. Reported means owner consensus with no hard confirmation, and never sets a risk level on its own.