This article we will show you how to set the time on your Mercedes-Benz S-Class, W220. To set the time on your instrument cluster, you first need to change the time on your Radio/Comand Unit. The two should synchronize with each other.

1. Mercedes W221 Reliability

Airmatic suspension failureThe Airmatic air suspension is part of standard equipment unless the car has the optional Active Body Control suspension (ABC).The ABC is a hydro-pneumatic suspension, and you can check if any particular W221 has the ABC by decoding the VIN number. The option code for ABC is 487.

Also, all V12 and AMG models have ABC as standard instead of Airmatic.Air suspension is commonly used in trucks and buses because vehicles with air suspension can maintain correct height and level despite the load. Have you ever seen a bus tilt and soon after level out when the passengers get off at the bus stop? That’s air suspension reacting to new conditions.The air suspension in Mercedes-Benz cars can react in the same way, and it’s capable of changing the ride height and damping stiffness. ABC suspension failureThe Mercedes-Benz W221 may be equipped with hydro-pneumatic suspension called Active Body Control (ABC). The ABC is standard equipment in the S 600 L and AMG models (S 63 AMG, S 65 L AMG).

It was an optional extra in other models, except cars with all-wheel-drive (4MATIC).When it works, the ABC exceeds what standard coil spring suspension can do. It is also better than the Airmatic suspension when it comes to handling. The ABC suspension is very comfortable, and at the same time, there is very little body roll when cornering or braking (hence the word “Active” in the name).The system can adjust the suspension position up to 5 times per second (5 hertz). Also, it is self-levelling, which means that it will maintain the ride height despite the load in the car.If you think the Airmatic suspension is complex, never buy a car with the ABC suspension. The ABC is a lot more advanced than the Airmatic, let alone a standard suspension. Anyway, the key points are:.The ABC is a complex, high-performance system and it will be more expensive to maintain than standard suspension or even the Airmatic.The ABC was improved in 2007.

If the high maintenance cost doesn’t scare you, and you still want a car with the ABC suspension, look for a 2008 model or newer.The age of the vehicle is important – the rubber hoses and seals age, which increases the likelihood of failure. The hydraulic hoses deteriorate and have a finite lifespan (they can burst). If a hose blows, the suspension shuts down. If you don’t stop on time, the hydraulic pump may die from running dry.

As you can see, it’s important to keep the hydraulic hoses in good condition.The nitrogen spheres last around 60k miles or 10 years, whichever comes first. They are service items and will need to be replaced regularly. Even if you don’t drive the car, the nitrogen gas will eventually escape, just like air escapes from a seemingly airtight balloon.The hydraulic pump will need replacing at some point (very expensive).

The pump has two sections – one that powers the suspension, the other runs the power steering.There are some options available on the market today that can help you save money servicing the ABC suspension: repair kits, aftermarket parts (Arnott has a good reputation) and reconditioned parts. Please be aware that it’s still going to be expensiveIf you’re still convinced that you want an S-Class car with the ABC suspension, here’s what to look out for:.Car dropping to quickly (on one corner or more than one) – visually check the car after it has been standing still for a couple days – the chassis should not be on the ground. According to Mercedes-Benz, a system in good working order should be able to hold the oil pressure at least for one week. If the car drops earlier, something is wrong with the valve block or there is a leak somewhere (probably a strut).Any ABC warning messages, appearing for a couple seconds when cornering, braking or after hitting a pothole, are bad signs. Before buying a car with the ABC, I recommend taking it to a professional to check the diagnostics log for any stored errors.Check the hydraulic fluid – it should be green.

If it’s dark brown, black or the fluid level is too low, it means the car has been neglected or maintained poorly. Do not buy such a vehicle. Running the hydraulic pump without oil will kill it very quickly.

The dark colour of the fluid means that it is dirty and full of abrasive particles – the entire hydraulic system could be worn out.Also, do not buy a car without maintenance history (including filter and hydraulic fluid replacements).Check the struts and the underside of the car for any oil leaks. Watch out for cracked dust covers on the struts (any damage there will accelerate the wear by allowing dirt and moisture in).Check that the car responds correctly, with no warning messages, to manually adjusting the ride height.Humming or howling noise between idle and 2000 RPM means that the pulsation damper has failed.The ride should be smooth and at the same time, there should be very little body lean when cornering or braking. If the car feels bouncy or hard, something is wrong.ABC suspension failure. M272 V6 & M273 V8 engine – soft balance shaft gearsThe M272 V6 engines are equipped with a balance shaft. A balance shaft is an eccentric weighted shaft, which is used to eliminate engine vibration.

It is driven by the timing chain as it needs to in sync with the engine pistons. A balance shaft is needed to make a V6 engine smooth because they are inherently unbalanced.The M272 engines manufactured between 2004 and 2008 were fitted with balance shaft gears and idler gears that can wear out prematurely. The M273 engines don’t have balance shafts but still have the defective idler gears.As these gears wear, the engine timing is altered due to increased slack in the timing chain. The first indication of a problem is the “ Check Engine” light and P0017 or P0016 error codes.

As the sprockets continue to wear, the engine will develop a rattle from the loose timing chain. All the while, more and more metal is being ground away from the gears.If not fixed, one of the gears may fail eventually and take the engine out (valves hitting the pistons).It is a problem that you should not ignore. The fix is to replace the gears with updated ones, which don’t wear out. It is very labour intensive, which makes it a very expensive repair.Not all M272 and M273 engines made before 2009 are affected. Engine serial numbers below have updated gears, which are free from the problem:.M272 engines with serial numbers higher than 2729. 30 468993.M273 engines with serial numbers higher than 2739.

30 088611Some engines seem to last despite having the unlucky gears, but I would not take the risk. In my opinion, affected engines are fine only as long as there is proof that the faulty gears (along with a number of other parts) have been replaced, and the engine is running well after the repair.M272 V6 & M273 V8 engine - soft balance shaft gears. M272 and M273 engine – variable intake manifoldThe intake manifold in these engines is very complex. It’s called a Variable (Length) Intake Manifold (VIM or VLIM), and it consists of three vacuum actuators, multiple levers, tumble flaps and valves that adjust the length of the intake tract.It’s not a very reliable design with lots of plastic parts that can fail.

When there’s a problem with the intake manifold, the engine performance is reduced (increased fuel consumption, loss of power, poor idle), and the “Check Engine” light may come on.The typical cause of failure is increased friction in the mechanism from the accumulation of oil and carbon deposits in the intake manifold. Additionally, over the years the plastic parts in the mechanism become weaker and more brittle.A couple of years ago you had to buy an entire manifold assembly to fix this problem (£800 at the dealership). Luckily, there are repair kits available on the market these days, which makes this a much smaller issue.If you are curious how carbon deposits and oil appear in the engine intake manifold – they come from the Exhaust Recirculation Valve (EGR) and Crankcase Ventilation System (CVS). These are standard systems used in virtually all road cars.M272 and M273 engine - variable intake manifold. M156 engine – head bolt corrosion (S 63 AMG)There have been cases of head bolt failures due to corrosion in the M156 engines. The head bolts are the fasteners that hold the cylinder heads in place. They are in constant tension to create a seal between the cylinder head and the engine block (engine block – head gasket – cylinder head).When the bolts start corroding, the clamping force may be reduced, which could allow coolant to leak into the combustion chamber or mix with the engine oil. A typical symptom is dropping coolant level while the oil level is rising.

If left untreated, the oil/coolant mix will eventually turn to sludge.Coolant entering the combustion chamber can also cause increased smoking and a rough idle.If any of the bolts holding the cylinder heads break off, a severe head gasket leak may appear. If the leak is large enough, the coolant entering the combustion chamber has the potential to hydrolock the engine.Hydrolock is a situation when the piston tries to compress the incompressible liquid. The liquid is not going to give in but something in the engine will – usually the connecting rods. To illustrate, here’s a photograph of a bent connecting rod after hydrolock (not from a Mercedes-Benz):Connecting rod of a Seat Arosa after HydrolockPhoto by MichaelXXLF;Mechanical engine damage is the worst case scenario, usually, the cars start losing coolant before failing like this.The head bolts were eventually updated by AMG around 06.2010. All engines made before this date are affected – engines with serial numbers beyond 569xx 60 060658 have the updated bolts. All cars produced before 2010/2011 may develop this problem. I believe that 2011 cars may be affected too.The M156 engine was replaced with the M157 unit in 2011.

Therefore, I recommend looking for an S 63 AMG with the newer M157 engine.Alternatively, you can buy the older S63 with the M156 as long as you can get a warranty that covers potential engine meltdown, or replace the head bolts preemptively. The percentage of engines that fail is small, as I see it, but it’s not worth the risk to me.M156 engine - head bolt corrosion (2006-2010 S 63 AMG). M156 engine – camshaft wear (S 63 AMG)Another weak point of the M156 engines are the camshafts, which are susceptible to premature wear. A typical symptom of a worn camshaft is ticking noise, initially only when the car is cold started. Over time, it becomes more persistent as the wear progresses.I believe that this is caused by a combination of too soft camshaft lobes and too hard cam followers.

The camshaft lobes are quite sharp (small nose radius), which may contribute to the problem. It’s not only the camshafts that can wear. Once a camshaft is scored and loses its profile, the cam followers can wear too – in severe cases to the point of breaking a hole in the centre.If you decide to get one of these cars, listen for a ticking noise for the first couple seconds after a cold start.

It’s the same procedure as checking for timing chain issues, so look out for any chain rattle too. If you hear a ticking noise, it’s likely the camshaft.

If you can hear a rattle which disappears after a couple seconds, it’s most likely the timing chain. Both types of noises are a bad sign.Also, regular oil changes are very important for camshaft life. You should avoid cars with incomplete service history.Here’s what a worn-out camshaft in the M156 engine looks like. M275 engine maintenance costsThe M275 is based on the M137 – a naturally aspirated V12 engine that had some issues. For example, replacing a leaking oil cooler in the M137 required the cylinder heads to be removed, which made it a very expensive job.The M275 is better in this regard, but it’s still a huge engine that fills out the engine bay completely, so replacing parts can be a nightmare.

Something as simple as changing the motor mounts may require the engine to be removed from the car. It is possible to do it with the engine in the car if you get creative, but my point is that even small repairs can be pretty expensive.There are 24 spark plugs and two ignition coil packs in this engine – one coil pack per cylinder bank. Each coil pack is an integrated unit that provides ignition for 6 cylinders. Imagine that you’re trying to fix a rough idle or misfire.

Replacing the spark plugs alone will cost £500 or more because it’s not as straightforward as in an average engine and because there is 24 of them.The coil packs fail occasionally and sometimes when there’s a misfire, replacing the spark plugs alone might not be enough. So you’ve already spent a lot of money on the spark plugs, and now you’ll try replacing the coil packs a single coil pack is around £800.If you compare this to the V6 M272 engine – a Delphi (OEM) ignition coil for the V6 is £40. There is one coil pack per cylinder and you can replace them individually, so it’s unlikely that you’ll need all six at the same time. I hope this gives you an idea what you’re getting yourself into when you buy a second-hand V12 Mercedes-Benz W221.M275 engine maintenance costs. M276, M278 and M157 engines – timing chain rattleWhen these engines first came out, some of them developed a timing chain rattle during a cold start.

The rattling noise is a result of the chain tensioners not applying enough tension until oil pressure builds up (a couple seconds after cold start).Mercedes-Benz was aware of the problem and came up with a fix documented in the Technical Bulletin LI05.10-P-056435. The repair involves fitting non-return valves (check valves) into the oil passages that supply oil to the two affected timing chain tensioners.The check valves prevent the engine oil from draining from the chain tensioners when the engine is off.The second step of the repair is to fit updated timing chain tensioners. This step is dependent on whether the affected car has the original tensioner design or already the updated one.

The chain tensioners had been updated before check-valves came into play, so not all rattling engines need new tensioners.The engine serial numbers below are affected (no check-valves or older timing chain tensioners used):.M276.8 engines up to number 276 8xx 30 001281.M276.9 engines up to number 276 9xx 30 406603 (February 2013).M278 engines up to number 278 9xx 30 103675 (February 2013).M157 engines up to number 157 9xx 60 022333 (December 2012)Unfortunately, the production of the Mercedes-Benz W221 stopped soon after the check valves were introduced. This means that nearly all (if not all) Mercedes-Benz W221 models with the M276, M278 and M157 engines are affected.If you are in the market to buy a Mercedes-Benz W221 with one of these direct-injection engines, definitely check if the engine doesn’t rattle during a cold start. I would even go a step further and call the dealership to find out if the particular car you are looking to buy has had the check valves fitted.Here’s what the timing chain rattle sounds like.

OM651 engine – premature timing chain wearThe OM651 engine is Mercedes-Benz’ first diesel engine with a single-row timing chain. Up until this point, all M-B diesel engines had dual-row timing chains that were superior in terms of durability and longevity.There have been reports of timing chains wearing out as early as 100,000 miles in the OM651-powered cars. To makes matters worse, the OM651 is the first Mercedes-Benz motor to have the timing gears in the back of the engine where access is restricted. This makes replacing the timing chain more expensive.I’m not trying to scare you. Failures aren’t that common. However, if you decide to get one of these cars, listen for any during the first couple seconds after a cold start. Follow this link to read more about timing chains and how to check them.OM651 engine - premature timing chain wear. OM651 engine – faulty piezoelectric injectors (S 250 CDI)The 125kW and 150kW OM651 engines were released with short-lived piezoelectric injectors made by Delphi.

The most problematic cars were the ones manufactured in 2009 and 2010. However, newer cars also experienced problems.In response to the failing OM651-powered cars, Mercedes-Benz initially decided to replace the faulty injectors with new ones, but eventually, scrapped the piezoelectric injectors completely. The final solution to the injector problems was to recall the cars to fit solenoid injectors, which is an older but proven technology.It wasn’t an official recall, but in reality, it kind of was. By now, most if not all faulty injectors should have been replaced. The original ones had been failing at relatively low mileage (even below 50,000 miles).

From mid-2012, the OM651-powered cars were fitted with solenoid injectors at the factory.If you are planning to buy an S 250 CDI BlueEFFICIENCY, get one that already has the solenoid injectors. Even if some cars managed to last this long with the piezo injectors, I’m not sure about the availability of spare injectors.If a piezo injector fails, you may be forced to have your car fitted with solenoid injectors. It would be very expensive to do so because it’s not a simple plug-and-play injector replacement (missing fuel return lines, new ECU required, four new injectors needed).To check if a particular car has the solenoid or the piezoelectric injectors, you need to remove the plastic engine cover.Here’s what to look for:.Piezoelectric injectors don’t have fuel return lines.

Mercedes W221 Reliability

The fuel return lines are rubber tubes that are attached to the injectors along with the metal fuel supply lines. If the car has fuel return lines, it has solenoid injectors.The sticker on the ECU should have the word “solenoid” on it in a car with solenoid injectors. The ECU is the shiny metal box that sits on top of the air filter housing. You will definitely see it once you remove the plastic engine cover.The sales brochures and old car reviews still say that the 150kW OM651 engine is equipped with state-of-the-art piezoelectric injectors.

Well, now you know that it’s not the case anymore.OM651 engine - faulty piezoelectric injectors (S 250 CDI). OM642 engine – oil cooler leaksThe pre-2010 OM642 engines were notorious for leaking oil from the oil cooler seals. The original seals (orange colour) weren’t able to withstand the heat and developed leaks. Updated seals (purple colour) were introduced in 2010.Ideally, get a post-2010 model with the updated seals. In the case of older cars, there was a recall for this issue.

Hopefully, most vehicles would have had the seals replaced by now. Before buying one, check if the seals have indeed been replaced and inspect the car for oil leaks.The seals are cheap. However, their replacement is expensive as the fuel injection system and intake manifold need to be disassembled to get to the oil cooler. The oil cooler sits on top of the engine, between the cylinder banks, underneath the intake manifold.

The symptoms of a leaking oil cooler are dropping oil level and oil underneath the vehicle after a longer stand still.OM642 engine - oil cooler leaks. OM642 engine – swirl flap motor failureThere have been cases of swirl flap motor failures in the OM642 engines due to contamination with engine oil. The swirl flap motor is located below the turbocharger and the turbo intake tends to develop leaks in this engine.

The oil leaking out from the air intake may get onto the swirl flap motor and cause it to fail.When the swirl flap motor fails, it puts the car in limp home mode along with turning the “Check Engine” light on. The air vented from the crankcase through the PCV system contains oil vapours. The PCV breather pipe is connected to the air intake before the turbocharger – that’s how engine oil gets into the intake manifold.Replacing the swirl flap motor is not as painful as replacing the oil cooler seals, but there is still a lot of parts in the way, and the motor itself is not that cheap.For this reason, people came up with a way to disable the swirl flap motor using a simple resistor to trick the car’s ECU into thinking that the motor is working. This solution is cheaper than replacing the faulty motor at the cost of more pollution.The swirl flaps are not essential for the engine to run – they are there to improve emissions and disabling them has a minimal impact on engine performance. Keep in mind that disabling emissions controlling equipment is considered illegal in most countries.OM642 engine - swirl flap motor failure. OM642 engine – Black DeathThe first two generations of CDI diesel engines may develop leaks from the fuel injector seals (copper washers).

When a leak occurs, the gases and the diesel fuel from the combustion chamber can escape and cover the area around the leaking injector with burnt, hard, tar-like substance.“Black death” is a dramatic name for something relatively inexpensive to fix, provided that you catch it early. Any leaks should be visible once the plastic engine cover is removed.If there was a leak, you will see a black mess on top of the engine. You may also smell diesel fuel inside the car when the engine is running. If the leak is large enough, the engine may sound like a steam locomotive due to gases escaping from the combustion chamber.If left untreated, it can become very expensive to fix – injectors seized in the cylinder head, damaged injectors seats and massive carbon build-up to clean.OM642 engine - Black Death. Summary of problems & additional information.In traditional Mercedes-Benz fashion, the W221 S-Class was available in short and long wheelbase versions in most markets. The S 600 L and the S 65 AMG were manufactured only in a long-wheelbase version.

The letter “L” indicates the long wheelbase.Corrosion was a big problem with the. Luckily for us, Mercedes-Benz got it right with the W221 S-Class. From the start of production, the W221 has a galvanized body and much better corrosion protection than earlier Mercedes-Benz cars.The Airmatic air suspension was standard equipment in the Mercedes-Benz W221 S-Class, except for the S 600 L and AMG models, which have the ABC hydro-pneumatic suspension. In other models, the ABC was an optional extra (option code 487). Both types of suspension are expensive to maintain, with the ABC being the more expensive of the two.Watch out for balance shaft and idler gear issues in the M272 and M273 engines. The balance shaft horror story and the overly complex variable intake manifold mechanisms are the only real issues with these engines. Once fixed, they are not bad units.

Unfortunately, Mercedes-Benz improved the balance shaft gears only in 2008. If you are going to buy a W211 with the M272 or M273 engines, be very careful not to buy one with worn gears. Look for a car that had them already replaced or one with updated gears – check engine serial number.The M156 was the first engine designed fully by AMG and not based on a Mercedes-Benz engine. Despite having excellent performance and winning multiple awards, this engine has its problems.

I recommend avoiding the S 63 AMG unless you are planning to do something about the head bolts that may corrode. Also, watch out for worn camshafts. A better choice would be to get the newer S 63 AMG with the M157 engine (from 2011).The direct injection petrol engines (M276, M278 and M157) may develop a timing chain rattle during a cold start.

The fix to this problem is to fit check-valves and updated timing chain tensioners as per Technical Bulletin LI05.10-P-056435. Before buying a car with one of these engines, make sure there is no timing chain noise during a cold start and that the check-valves have been fitted (contact a Mercedes-Benz dealership).Also, be aware that carbon build-up on the intake valves is a possibility in the M276, M278 and M157 engines because of the direct fuel injection.for an article that might help you decide if a modern diesel engine, like the Mercedes-Benz CDI, is the right choice for you.

All diesel engines in the Mercedes-Benz W221 S-Class have diesel particulate filters (DPF).The pre-2010 OM642 engines may suffer from oil cooler leaks if the seals haven’t been replaced yet. Also, the swirl flap motor design is unfortunate in this engine. However, this is a much smaller problem than leaking oil cooler seals.I can’t recommend the OM651 engine (S 250 CDI) because of potential problems with the timing chain, which is at the back of the engine. Also, these engines experienced problems with the original piezoelectric fuel injectors.

By now, most of the OM651 engines have the retrograde solenoid injectors, which turned out to be more reliable. I think that Mercedes-Benz tried to stay too close to the cutting-edge when designing the OM651 engine.All Mercedes-Benz W221 engines are fitted with timing chains, which normally don’t have a specified replacement interval. Unfortunately, some of the engines in the W221 may develop issues (OM651, M272, M273, M276, M278 and M157). Read more about and how to check them before buying this car.Please be aware that Mercedes-Benz is a manufacturer of high-performance, luxury cars. High performance usually goes hand in hand with increased complexity. This is particularly true for the S-Class, which has been Mercedes-Benz’ testbed for the latest technologies.

The features you see in an S-class car today may be popular in more ordinary cars in a few years. When things go wrong, you can expect the servicing costs to be above average.The V12 W221 models are very expensive to maintain. Pick your model wisely – there will be a big difference in maintenance costs between an S 350 and an S 600 (more parts, ABC suspension, restricted access in the engine bay).The S 400 HYBRID was the first Mercedes-Benz hybrid car and the first hybrid car that used lithium-ion batteries. Well, this is partially correct because the first Mercedes-Benz hybrid was a bus:The Mercedes-Benz OE 302 was a hybrid bus with a direct-injection diesel engine, 150kW electric motor and regenerative brakes – not bad for 1969!Summary of problems & additional information. EngineEngine config.Forced inductionValve timingFuel deliveryDMFInlet flapsLegend:SOHC - Single Overhead CamshaftDOHC - Double Overhead CamshaftVVT - Variable Valve TimingEFI - Electronic Fuel InjectionDMF - Dual-mass Flywheel (does not apply to auto. Transmissions with torque converters)VLIM - Variable Length Intake ManifoldM272V6, 24 valvesNoTiming chain, DOHC, VVTPort injection (EFI)Auto.

Trans onlyYesM276V6, 24 valvesNoTiming chains, DOHC, VVTDirect injectionAuto. Trans onlyVLIMM273V8, 32 valvesNoTiming chain, DOHC, VVTPort injection (EFI)Auto. Trans onlyYesM278V8, 32 valvesParallel twin turboTiming chains, DOHC, VVTDirect injectionAuto. Trans onlyNoM156V8, 32 valvesNoTiming chain, DOHC, VVTPort injection (EFI)Auto. Trans onlyNoM157V8, 32 valvesParallel twin turboTiming chains, DOHC, VVTDirect injectionAuto.

Trans onlyNoM275V12, 36 valvesParallel twin turboTiming chain, SOHCPort injection (EFI)Auto. Trans onlyNoPetrol engines - technical details. EngineEngine config.Forced inductionValve timingInjection systemDMFDPFSwirl flapsLegend:DOHC - Double Overhead CamshaftDPF - Diesel Particulate FilterDMF - Dual-mass Flywheel (does not apply to auto. Transmissions with torque converters)OM651Inline-4, 16 valvesSequential twin turboTiming chain, DOHCCommon RailAuto trans.

All combined to the user-friendly, beautiful interface.

OnlyYesYesOM642V6, 24 valvesSingle turbochargerTiming chain, DOHCCommon RailAuto trans. OnlyYesYesOM629V8, 32 valvesParallel twin turboTiming chain, DOHCCommon RailAuto trans. OnlyYesYesDiesel engines - technical detailsMercedes-Benz W221 wheel sizesPress the button below to see the original equipment manufactuer (OEM) rim & tyres sizes for the Mercedes-Benz W221. These are the original wheel sizes that were fitted by the manufacturer. TyresRimsCentre BoreBolt PatternComments235/55 R178Jx17 ET4366.6mm5x112255/45 R188.5Jx18 ET4366.6mm5x112255/45 R18 front & 275/45 R18 rear8.5Jx18 ET43 front & 9.5Jx18 ET43 rear66.6mm5x112Staggered setup255/40 R198.5Jx19 ET4366.6mm5x112AMG wheels255/40 R19 front & 275/40 R19 rear8.5Jx19 ET43 front & 9.5Jx19 ET43 rear66.6mm5x112S 63 AMG, S 65 AMG & AMG Sports Package, staggered setup255/35 R20 front & 275/35 R20 rear8.5Jx20 ET43 front & 9.5Jx20 ET43 rear66.6mm5x112S 63 AMG, S 65 AMG & Sport Package Plus one, staggered setupOEM rim & tyre sizesShare this page.

If all of the locks on your Mercedes fail to open (or close) first check your key fob to make certain that its battery is working. Replace the worn out battery, if necessary.

If key fob is working, you may have a faulty key fob, which can be repaired or replaced by taking it to your dealer. If just one lock won't open on your Mercedes, then the problem may rest with broken wiring, a bad solenoid, or perhaps with a blown fuse. Check your fuse box first to determine if a blown fuse is keeping the lock from working. If so, replace the fuse.

You likely have a shorted door lock actuator, which you can replace with a new unit for the lock that is not working. If a door unlocks, but will not lock again, then replace the door switch. Perhaps your Mercedes locks work, but they open and close slowly. Apply WD-40 or equivalent product directly into the lock; open and close lock to recalibrate. The National Highway Transportation and Safety Administration (NHTSA) issued a recall for select 2009 Mercedes S-Class sedans. That recall involved fixing the side door locks on affected models which might have been exchanged during production.

According to the NHTSA, '.the exchange of a front and a rear passenger side door lock would result in a passenger side door that cannot be opened by merely pulling on the interior handle and a rear door lock that can be opened with a simple pull of the interior door handle even if locked.' If you own this make/model/year car, contact Mercedes-Benz at (800) 367-6372 for assistance.