About this model
The Mercedes-Benz E-Class W212 was built from 2009 to 2016 and was one of the best-selling luxury sedans in Europe during that period. In BiH it is most commonly encountered as a used import from Germany, Switzerland and Austria, almost exclusively in diesel versions - 200, 220, 250 and 350 CDI. Our shop sees mostly the E220 CDI with the OM651 engine (170 hp in the first series, 170-204 hp in later variants). It is a car that in BiH often crosses 300,000 km, but only with disciplined maintenance - the W212 forgives less than the older W211 generation. Buyers choose it for its reputation, space, motorway manners and the fact that spare parts are plentiful on the regional market.
Engines and variants
This model is most commonly available in BiH with the following engines.
OM651 (E200 CDI, 136 hp) - the weakest diesel version of the OM651 family, but with an important advantage: it often came with magnetic Bosch injectors instead of the piezo Delphi system. It is less prone to the classic injector problem that plagues the 220 and 250 CDI variants. The other OM651 issues (timing chain, EGR, DPF) are present to the same degree as on the more powerful versions. Buyers who don't need 170 hp gladly pick this variant precisely because of the calmer injector setup.
OM651 (E220 CDI, 170 hp) - the most common variant on the BiH market and the reason this article exists. A good compromise between power and fuel consumption, it cruises calmly on the motorway and isn't too thirsty in town. It is the most prone to issues with piezo Delphi injectors on early examples (2009-2012). When buying, it's essential to check the history of injector replacements and ask for a cylinder balance test on the diagnostic tool. Spare parts are widely available, which keeps repairs reasonable.
OM651 (E250 CDI, 204 hp) - the bi-turbo version that squeezes the most power out of the 2.1 diesel unit. The piezo injectors remained a problem throughout the entire life cycle because Mercedes did not switch to the more reliable magnetic injectors on this variant. The added stress of the bi-turbo system means stricter oil service and more careful turbocharger maintenance. In BiH it is less common than the 220 CDI variant, but it has its own following among drivers who want more power with diesel economy.
OM642 V6 (E350 CDI, 231-265 hp) - the V6 diesel for the top variants. It is smoother and stronger than the OM651, but more expensive to maintain. It has its own set of issues (cracked intake manifold, dual-mass flywheel, oil cooler) that differ from the OM651. In BiH we see it less often than the E220 CDI because it is more expensive to maintain and consumption is higher, which makes it less attractive on the local used market.
Reliability and reputation on the BiH market
The W212 with the OM651 engine is a car with the potential to cross 400,000+ km, but only if money has been put into it. The difference between a good and a bad W212 at 250,000 km is huge - it depends almost entirely on whether previous owners kept to the service interval and used quality oil and fuel. Spare parts are available both as original and as quality aftermarket - Banja Luka and Sarajevo have solid supply channels, and used components from Germany arrive quickly without major waits.
Compared with rivals from that period (BMW F10 530d, Audi A6 C7), the W212 sits somewhere in the middle - less sensitive than the F10 530d at high mileages, but more demanding than the older W211, which had simpler mechanicals. In the shop we most often see vehicles between 180,000 and 320,000 km, almost all of them imported from the German-speaking region. It tends to be bought by more serious drivers, usually 45+, who want motorway comfort and are prepared to pay for regular service at a specialist garage. The car isn't for someone hoping to buy a used Mercedes and run it on minimal investment - with the W212 that simply doesn't work.
Common faults we see
From practice, here is what most often comes in for repair on this model.
1. Piezo injectors (Delphi) - the OM651's most famous weakness
Symptom: Rough idle, jerking under acceleration, increased fuel consumption, smoke from the exhaust, stalling on throttle release, and stored fault codes related to cylinder balance.
The early OM651 (2009-2012) on the 220 and 250 CDI variants came with piezo Delphi injectors without leak-off pipes, which proved sensitive to fuel quality and overheating. Mercedes later switched to redesigned injectors with a return line for excess fuel, but used examples in BiH often still have the originals, or have only had partial replacements. The problem can show up below 150,000 km if the car has been run on poor fuel.
Advice: When buying, ask for a cylinder balance test on the diagnostic tool and check whether the injectors have been replaced as a full set. Don't buy a car where only one has been changed - the rest will follow.
2. Timing chain and tensioner
Symptom: Rattling (ticking) from the front of the engine on a cold start, fading once the engine warms up, fault codes related to camshaft/crankshaft correlation, loss of power.
The OM651 has two chains in series - the main chain and the balance shaft chain - and is known for premature chain stretching. Mercedes redesigned the chain and sprocket set several times. On top of that, a recall was issued in Germany in 2014 for a large number of OM651 engines due to seal rings on the chain tensioner leaking oil. Vehicles built during 2014 are a risk group.
Advice: If you hear a cold-start rattle - don't put it off. A snapped chain on the OM651 means a full rebuild. We replace it with a preventive tensioner update and always check the seals.
3. Balance shaft and its chain
Symptom: Cabin vibrations that grow with mileage, unusual engine noise, intermittent camshaft fault codes.
The balance shaft chain on early OM651s (up to around 2012) wore faster than the main one. Once it stretches, the balance shaft goes out of phase and vibrations start, which the driver feels through the steering wheel and the seat. Owners often think the problem is in the engine mounts, while the real culprit is the internal chain.
Advice: When in doubt we always take the cover off and check both the main and the balancer chain at the same time. Replacing them in separate jobs is money wasted on tear-down labour.
4. EGR valve and EGR cooler
Symptom: Loss of power, smoke, check engine light, rising fuel consumption, fault codes P0401/P0402 or Mercedes-specific EGR valve codes.
Like every modern diesel, the OM651 uses EGR to reduce emissions. After 150,000-200,000 km, depending on driving conditions, the EGR valve and cooler get clogged with a mix of soot and crankcase oil vapours. On some examples the EGR cooler cracks too, which means coolant in the intake manifold - typically you'll see white plumes of steam at the exhaust.
Advice: We don't recommend EGR delete via software because it won't pass technical inspection, but a mechanical clean at 80,000-100,000 km, depending on use, gives the engine a new lease of life. We pressure-test the cooler.
5. DPF (particulate filter) and pressure sensors
Symptom: The car goes into regeneration too often, DPF light, loss of power into limp mode, smell and smoke, fault code related to differential pressure.
City driving on short trips is the worst scenario for the DPF on the OM651. In BiH, cars from Germany often arrive with the filter already loaded because the last years of their life were spent in town. Beyond the filter itself being dirty, the problem is often in the differential pressure sensor before and after the catalyst.
Advice: First we check the sensor (which is reasonably priced), and only then we move on to forced regeneration or filter cleaning. We don't recommend cutting out the DPF, even though it's common in BiH - technical inspection and ecological registration become a headache.
6. Vacuum pump and oil leak
Symptom: Hard brake pedal (loss of servo assistance), oil dripping on the engine block, fault in the braking system.
The tandem vacuum pump on the OM651 (which also drives the high-pressure oil pump) is known to let its seal rings slip and leak oil, and to lose vacuum as well. It most often happens above 200,000 km. A hard brake pedal in the morning is a classic sign.
Advice: The pump is replaced as a set with its matching seals. We don't improvise - it's either an original part or a quality aftermarket equivalent.
7. Swirl flaps in the intake manifold
Symptom: Jump in fuel consumption, loss of power at low rpm, uneven running, fault codes related to the flap position sensor.
The plastic flaps in the intake manifold wear, break or the actuator motor gives up over time. If the flaps drop into the engine - catastrophic damage. The good news is that the OM651 isn't as notorious for total flap disintegration as the older OM642, but actuator failures are common.
Advice: During every EGR clean we also check the condition of the flaps and the actuator. Plastic that's starting to crumble gets replaced preventively.
8. Water pump and fuel filter housing
Symptom: Coolant leaking under the engine, smell of antifreeze, slight overheating in stop-go traffic. With the filter housing - diesel leaks, hard starting.
The water pump on the OM651 has a limited life - usually 150,000-200,000 km, depending on driving conditions and antifreeze quality, and the seal quality isn't the best. Similarly, the plastic fuel filter housing tends to crack or leak at its connections. These are small things that, if ignored, lead to bigger problems (overheating, air in the fuel system).
Advice: We replace the water pump along with the thermostat once we're already in there. Fuel filter at the proper interval - 30,000 to 40,000 km, not when you happen to remember.
OM651 cold-start rattle - what should I do
This is the most common specific query we get on the phone about the W212. If you hear a short rattle from the front of the engine for the first 3-5 seconds after a cold start that disappears once the engine warms up - that is almost certainly a sign of a stretched timing chain or a worn tensioner. No need to panic, but no need to delay either. The car can drive with that symptom for several more months, but every kilometre past that threshold raises the risk of chain skip, and a chain skip means a full engine rebuild. The smart move is to come straight in for diagnostics and a camshaft/crankshaft correlation reading - that shows how stretched the chain actually is and whether there is time for a planned replacement or whether it's urgent.
Service and maintenance
The timing chain on the OM651 is not lifetime - we recommend a check every 150,000 km and a preventive replacement of the chain set (main + balance) in the 200,000-250,000 km range, depending on driving style and service history, together with the tensioner and guide rails. Oil: MB 229.51 or 229.52 (depending on year) in 5W-30 viscosity, interval 10,000-12,000 km - not the longlife 20,000-25,000 km that Mercedes nominally calls for, because our fuel and short urban trips destroy oil faster. Fuel filter - at 30,000-40,000 km, don't skip it. The DPF and EGR system want a mix of city driving and motorway; if the car has been driven almost exclusively in town, plan an EGR clean and forced DPF regeneration as routine work in the 80,000-100,000 km range, depending on conditions.
Which oil for the OM651 engine
Specifically for the OM651: synthetic 5W-30 with Mercedes MB 229.51 specification (for vehicles with a DPF, which is essentially the entire OM651 programme in BiH) or MB 229.52 for newer examples. Don't compromise with generic 5W-30 that doesn't carry MB certification - the additive package isn't the same and the timing chain feels it first. A quality oil filter, original Mercedes or Mann/Mahle/Hengst. Interval 10,000-12,000 km in BiH conditions, not the nominal 20,000-25,000 km that Mercedes advertises as longlife.
Owner tips
- Before buying a specific example: use the VIN to pull the car's full history through carVertical. From international registries it typically shows actual odometer readings by date, recorded accidents, the number of previous owners, and theft or total-loss indicators. For German and Swiss imports like the W212, we consider it mandatory before any deposit. When paying for the report, you can use code GAGA and get a 20% discount.
- Change the oil at 10,000 km maximum, with MB 229.51 or 229.52 specification, regardless of what the service book says about 25,000 km - the longlife interval kills the chain and the injectors in BiH conditions.
- If you hear a cold-start rattle from the front of the engine - get it on the diagnostic tool right away, don't wait. The chain on the OM651 doesn't forgive delays.
- Drive at least 30 km of motorway every few hundred kilometres so the DPF can regenerate - short urban trips clog the filter and the oil gets diluted with fuel.
- Check the vacuum pump and water pump visually at every service - oil dripping from the pump and the smell of antifreeze are early signs that save thousands later on.
Frequently asked questions
Is the OM651 engine reliable and is a W212 with 250,000 km worth it?
The OM651 is a reliable engine when it has been serviced regularly - we know examples that have crossed 450,000 km. With 250,000 km, a W212 only makes sense if it has a clear service history (chain, injectors, EGR), if it has been through detailed diagnostics, and if all the sensitive spots - vacuum pump, water pump, DPF sensor - are known to be in order. Without a service book and a pre-purchase inspection, the risk is significant.
What is the difference between the first-series E220 CDI and the facelift (2013)?
The 2013 facelift brought a redesigned front and rear, a new interior and, on some variants, updated injectors. Mechanically the OM651 stayed the same, but on slightly newer examples the piezo injector problem shows up less often - they moved to a more reliable setup. The second series is generally the better choice if the budget allows.
How much does timing chain replacement cost on the OM651?
The price depends on the specific condition - get in touch for a quote. Factors that affect it: whether only the main chain is being replaced or the full set (main + balance + tensioners + sprockets), the quality of parts (original Mercedes or quality aftermarket), and how many hours of labour are needed. We do diagnostics and a condition assessment first, because you don't always have to replace everything at once.
Can I fit LPG to a W212 E220 CDI?
No - the E220 CDI is a diesel engine, and LPG cannot be fitted reliably to diesels. Dual-fuel systems for diesels do exist, but we don't recommend them in our shop - they stress an already sensitive OM651 and complicate maintenance. If you want LPG, go for the petrol variants of the E-Class (E200, E250 petrol).
Which is the best oil for the OM651 and how often should it be changed?
Synthetic 5W-30 with Mercedes MB 229.51 or 229.52 specification (depending on year). Interval - 10,000 to 12,000 km, not the nominal 20,000-25,000 km longlife that Mercedes advertises. Our fuel, short city trips and dust call for a shorter interval. A quality oil filter is a must.
How do I spot a used W212 whose injectors are about to give up?
The diagnostic tool shows the cylinder balance - if one cylinder is constantly out of spec, the injector is suspect. Listen for whether the engine knocks at idle, whether there is white or grey smoke from cold, and check whether a cylinder balance fault has been logged in memory. A car that stalls or jerks on throttle release - almost certainly the injectors.
Is the W212 a good choice for the motorway and long international trips?
Absolutely - the W212 is a sedan built primarily for the motorway. Comfort, stability and consumption at a steady speed are among the best in class. The OM651 loves the motorway because it actively regenerates the DPF and doesn't suffer from short urban cycles. If your daily route is a long stretch - the W212 is an excellent candidate.
If you spot any of these symptoms on your W212, drop into the shop - it's better to check early than to pay for an expensive repair later.