I’m going to start this off by saying that before you even start shopping for a modern (~1990+) Mercedes-Benz, you should start shopping for a diagnostic scanner! While you are finalizing purchase details and arranging with a seller to check out a car for sale, your scanner should be in the mail to you. You should have your new scanner in hand when you go to see a potential car!
Owning your own scanner will save you thousands and thousands of dollars on unnecessary repairs and mis-diagnosis costs over just a couple of years. You can NOT afford to own a modern Mercedes, especially a W220 car without owning a proper diagnostic scan tool. Even the most expensive scanner will pay for itself over and over again.
Now, I need to say that I talk bad about auto repair shops ALL THE TIME and I need to put a little disclaimer that there are some absolutely fantastic shops out there. If you find one, stick with them! Their prices are usually a bit higher than the garage down the street whose lot is packed with Ford Tauruses and Chrysler PT Cruisers but a proper diagnosis and repair costs a lot less than slinging thousands of dollars worth of parts at a problem. MOST shops out there simply do not know how to properly diagnose W220 Mercedes S-Class cars. In all fairness, they are busy trying to handle many makes and models and there just isn’t enough time in the week to learn the ins and outs of all vehicles. There is also specialty software and specialty tools for every make and model. Replacing control arm bushings on some Mercedes is literally a 20 minute job but requires a $900 tool to do it! Most shops can’t afford to spend that kind of money on a tool that they will use once or twice. It will never provide for a return on investment. The same holds true for scanners, especially when you have to buy a Land Rover scanner, a BMW scanner, a Mercedes scanner, etc, etc. Before you know it, you have $100k tied up in scan tools that you don’t have time to learn how to use. What usually happens is those shops go out and buy an expensive Snap-On scanner that handles many makes and models. A single $10k purchase now covers 95% of the work they will need to do. Anything else they can take shots in the dark at or farm out to someone else. Those scanners work great on domestic vehicles like Chevy or Ford and they also work pretty well on a lot of Japanese cars like Honda or Subaru. Unfortunately for us, the Germans tend to be a little harder to deal with. VW, Audi, Porsche, BMW, Mercedes; these all require their own make specific scanners to be able to efficiently diagnose and repair. The newest cars require the specialty scanners to simply replace the battery! You need to have a $10k scanner to replace your own battery on some cars now! At any rate, what this all leads to is a shop that doesn’t have the right tools for the job and is trying to make due with what they do have. This more often than not leads to inaccurate diagnosis and tons of time wasted. Generic scanners, even the expensive ones, can only pull the codes that throw a check engine light or other warning light. Most will not read the suspension module or your PSE equipment, etc. There are some that do and we will go into those down below.
The good news for you is that you don’t have to work on all makes and models of car. You can buy the correct scanner for your Mercedes and start diagnosing it yourself. Let’s cover some of the systems below and their pros and cons.
1: Carsoft i980 and iCarsoft MB II
These scanners (at the time of writing) are $95 and $187. There is no cheaper option. The iCarsoft MB II is supposed to be the newer version of the Carsoft i980 but the MB II has been out for well over a year and they are still selling the i980. I have extensive experience with the i980 but no first hand experience of the MB II. The MB II appears to do all of the same things as the i980 with what looks to be a better interface. I see no functionality change between the two. Documentation for these scanners is severely lacking and even information provided by the manufacturer is not correct. Do not trust the feature list.
The i980 is a great little scanner. I have one in the shop alongside all of our other equipment and it is usually my go-to scanner for quick diagnostics. It works on W220 cars but will not always read all the modules. It will not do programming of any kind and it can not run tests. It will pull almost all codes, even manufacturer specific ones that OBDII scanners can not pull out. It can also reset these codes. I consider this device to be a “monitor” device. You can see pretty much everything that is going on and it can get you on the path to solving most problems very quickly. This is well worth the investment but it does come with some limitations. It is hit or miss on connecting to some modules, like the ESP modules. I’ve had cars where it couldn’t connect at all and some where it works just fine. Keep in mind that this device is not a high end device and it’s goal is to get you most of the way there with minimal investment. If you know going into it that it will have limitations, I think you will be happy.
2: Autel MaxiDAS DS708
The MaxiDAS DS708 is a fantastic scanner for the price. It completes almost everything that an expensive Snap-On SOLUS can do. This is a multi-car scanner so it will also work on almost any other make and model car. This computer will reliably connect to every module on the W220 Mercedes cars. It will pull all of the manufacturer specific codes and it will run most tests. It will not get you any access to the Developer Mode functions, programming and coding modules is limited, and some tests are iffy, like setting ride height or variant coding. This tool will cover almost everything you will need. The interface is intuitive and easy to use. This is a highly recommended tool. If you have a limited budget and many cars to work on, this is the tool I would recommend.
3. Mercedes STAR/DAS system
This is the real computer system you need for working on Mercedes vehicles, especially W220 cars. The Mercedes STAR diagnostic system will accomplish everything the dealer can and is relatively easy to learn the basics of. These systems go for anywhere from $600 for the older STAR C3 with a Dell D630 laptop up to $1600 for the newest C5 diagnostic system with the EVG7 tablet. The different models do different things but for the W220, the only difference is the speed of everything and wired vs wireless. Even the C3 will perform all the functions necessary on the W220 including programming, variant coding, module swaps, anything you need.
If price is an issue, go with a C3 and D630. This system has been out for a long time. It is reliable, cheap, and easy to find. It is very slow but for personal use, that isn’t an issue. Boot up time of the computer is the worst. Once the computer is running and the XENTRY application is launched, it isn’t bad at all to work with. It’s just the setup that is annoyingly slow.
The C4 is the first of the wireless options. You still need to plug the multiplexer into the car but the connection from the computer to the multiplexer is wireless. This allows a little more freedom of movement and also limits the risk of scratching paint or tripping over cords. The wireless in the C4 has been reported to be a little unreliable but I’ve personally had very few issues with it. Most issues are resolved by simply restarting the machine. The C4 doesn’t improve on speed since the speed issue is that of the computer itself. The D630, even fully upgraded, will never be anything close to fast. Some sellers can use a Panasonic Toughbook. I like the Toughbook waaay more than the D630. It’s slightly faster but the real selling point is the durability. It’s very water resistant, has a fully swiveling and folding screen. You can turn it all around or fold it down to use as a tablet. It’s a touchscreen which is nice but I never use the touchscreen capability. The keyboard is faster.
The C5 is the newest version and works great. The wireless seems to have more range than the C4 and connecting is fast and simple. Combined with the EVG7 tablet, the system is incredibly fast. If you have the money, it’s absolutely worth the extra expense for shop use. For personal use where time isn’t so much of an issue, the other models work fine. The tablet is a little annoying in that it is a touch screen and a little small. You tend to hit the wrong menu options a lot and typing in stuff is frustrating with the little on screen keyboard. The size of it and the speed more than make up for the downfalls.
If you want to purchase a STAR diagnostic system, you will need to head over to aliexpress.com and search for “mercedes c3 diagnostic” or similar. It will bring up many options for purchase. These systems all come from China so expect a delay in shipping and limited technical support. These systems all require some degree of computer literacy. If you can’t figure out how to install drivers or troubleshoot network issues, owning a STAR diagnostic system might be challenging. Sometimes the systems can be found on eBay from US sellers but usually at a markup since they just buy them from aliexpress.