MajorCommonEngine

Mercedes-Benz Vito: OM646 Injector Copper Seal Failure — Carbon Seizure

OM646 Injector Copper Seal Failure — Carbon Seizure is a common engine fault on the Mercedes-Benz Vito on the 2003–2014 cars, and we rate it major. Putting it right costs $600 to $4,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 16 documented faults on the Mercedes-Benz Vito.

Vehicle: Mercedes-Benz Vito
Engine: 2.1L
Years: 2003–2014
Fuel: diesel
System: Engine

This page covers the Mercedes-Benz Vito as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Mercedes-Benz Vito faults16 documented faults on this model

What you are looking at

What goes wrong

The OM646 2.2CDI engine uses copper crush washers to seal diesel injectors in the cylinder head. When these seals degrade or are not replaced at injector service intervals, combustion gases escape past the injector base and carbonise on contact with cooler head metal, building up a hard expanding deposit around the injector body. This condition is widely termed Black Death in Mercedes specialist circles. The accumulated carbon can bond injectors solidly to the head, making extraction extremely difficult and expensive. Severely locked injectors risk breaking during removal, potentially requiring cylinder head replacement.

What you would notice

Black carbonised crust visible around one or more injector bases at the cylinder head
Rough running or misfires on the affected cylinder
Diesel smoke visible from the engine bay near the valve cover area
Hard starting or poor cold-start performance

How to check it

Where to look. Cylinder head, at each injector base on top of engine

Any black, hard, carbonised crust around an injector confirms copper seal failure and ongoing combustion gas escape. Note how many injectors are affected and the severity of carbon buildup, as this determines extraction difficulty and cost. Ask whether injector seals have been replaced at service. If a workshop inspection is possible: Remove the engine top cover and visually inspect the base of every injector where it enters the cylinder head.

Parts involved: Fuel injector.

What it costs to put right

$600 to $4,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Have the injector copper seals been replaced, and when?”
“Is there any visible black carbon crust around the injector bases under the engine cover?”
“Has the vehicle ever misfired or run roughly on one cylinder?”

Now check the Mercedes-Benz Vito you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Mercedes-Benz Vito buyer questions

Is om646 injector copper seal failure — carbon seizure serious on a Mercedes-Benz Vito?

We rate it major and common on the Mercedes-Benz Vito. The OM646 2.2CDI engine uses copper crush washers to seal diesel injectors in the cylinder head. When these seals degrade or are not replaced at injector service intervals, combustion gases escape past the injector base and carbonise on contact with cooler head metal, building up a hard expanding deposit around the injector body. This condition is widely termed Black Death in Mercedes specialist circles. The accumulated carbon can bond injectors solidly to the head, making extraction extremely difficult and expensive. Severely locked injectors risk breaking during removal, potentially requiring cylinder head replacement.

How much does it cost to fix on a Mercedes-Benz Vito?

$600 to $4,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Mercedes-Benz Vito years are affected?

Our research records this fault on the 2003–2014 Mercedes-Benz Vito. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.