DIY Maintenance

How to Change Mercedes Key Battery

This is a really quick video on replacing your Mercedes-Benz Key Fob battery.

These tend to go in pairs, so if you are prompted to change one, it is a good time to change both.

These take CR 2032 Batteries and can be found on Amazon here: (affiliate link).

DIY Electronics Maintenance Performance

Laser Jammer Install on E class w212

Check out this install thread on for AL Priority Laser on a w212.

Very clean and detailed with some help from other members with CAD information on the mounts.

I am not advocating the use of this, but I do love clean installs and have to link to it for that reason.

DIY Maintenance

Don’t check your oil when cold

While driving in the middle of NC between DC and FL, I made the mistake of checking my oil. It read low, really low.  I panicked and added some oil.  Later I was racking my brain over why the oil level seemed to vary so much depending on the reading.

If it was cold, over night cold, the dipstick indicated too high.

Right after running oil seemed too low.

20 minutes after running the oil was in the middle.

And so I wanted to test it out.  I filled the oil to cold full.  Within 30 minutes of driving I got a "check oil at next refueling" message which roughly translate as I understand it to add 1 liter of oil.

I went further down this rabbit hole and found Mercedes recommends in the owners manual running the engine until hot, then waiting at least 5 minutes to measure the oil.  This seemed to indicate a bit high to me.  When filled to this level the engine would rattle a bit more and was noticeably louder.

I would guess the best way to do it is to drain everything and set to specifications 8 liters.  I will add some pictures of what I would guess the correct indicator is when cold, hot, and just right.

DIY Maintenance

Change Cabin Air Filter in Mercedes

If you're running high flow cats, or no cats on a race application, it is recommended to change your cabin air filter more often than the every b service.

Changing the air filters, like the spark plugs, is a little harder than on a toyota.  Instead of just going behind the glove box, you have to go under and then back up like the plot line of a 1990's Arnold movie.

The Under

Under the glove box there are three T25 screws,  these are held in place by little metal things that attach to plastic (they can be slightly misaligned upon reinstall which is why I am foreboding with this information).

You then pull up the carpet toward you and bend the plastic piece away from two plastic pieces one on the footwell area and one next to the door where the black meets.

Then you pull the black piece under the glove box aft and down.

There are two wires which are fairly fragile and paradoxically some how also difficult to remove.  I have no idea what one of them is for, and the other is for a light. I have broken the mysterious side, and nothing has happened so I guess I'll reattach the wires back into the connector at some point.

The Back Up

Once you have ventured the under it is time to look back up and then remove the filter by sliding a white clip to an area that there are no more retaining tabs.  The filter pulls downward.  A new Mercedes cabin filter fits in one direction. The tab starts in the opposite direction for reinsertion. From where there is no retaining clip then slide over to where they overlap and the clip now holds the filter.

Before you put everything back in reverse order add some felt treatment on the plastic on plastic areas to reduce rattling.  I also opted to add a bit of dynamat on the pieces that exhibited undamped harmonics when tapped.

Another Take

Check out this write up on MBworld.  Seems somewhat deprecated and without pictures, but may be useful:

DIY Stereo

Upgrade Mercedes Tweeters in CLS

Previously, I purchased a set of speakers to fit into the front.  I was only able to ft the woofers at the time but it made a huge difference.  The dynaudio tweeters and mid did not fit.  The screen I previously upgraded but haven't yet done a video on.

Later I upgraded the MB CLS rear woofers and then added inductors to them but honestly it didn't make as big of a difference. The rear woofers cut over at 80hz, the front at 60hz.

With the upgraded front woofers, I decided it was time to take on the tweeters as they became muddy and distorted at higher volumes now that I've tamed some of the front & rear rattles.

Upgrade front tweeters in a Mercedes with Harmon Kardon

Upgrading the front tweeter is not difficult at all. You do not need to remove the door card, but you will need to add a capacitor inline to protect it.  I choose to use the capacitor from the JL C2 crossover which reduced the crossover frequency allowing the front tweeter to play approximately 2000hz deeper than the oem MB HK front tweeter.  Approximately 6500hz with 6 MFD mylar aftermarket cap acting as a 1st order crossover, so some sound down to 3250hz would be audible at -6db, vs  ~8500hz with 4.7MFD stock 1st over crossover, which could be heard again at 4250 at -6db.

Tweeter Upgrade in Mercedes CLS c218 w218

This actually helped staging quite a bit more than I thought it would.

I have a set of mids ordered for the front doors and the install is written up: upgrade mercedes mid woofers

DIY Stereo

Reduce Bass Rattle from Rear of Mercedes CLS or E-Class

I really enjoy driving my CLS.  I do remember though the speakers would rattle, the doors would rattle; I drove over a rough patch of road and I thought to myself, "why did I trade in my avalon."  That is how bad the speakers and rattle were.

Slowly, piece by piece, door by door, I began to dynamat everything that rattled.  Dynamatting the front doors (and adding new woofers) paid out huge and completely stopped rattling that used to occur by the front arm rest.

I got to a point though when I didn't know what to do next.  I turned to the mbworld for suggestions.  I sound treated the rear grill, and later the area where the back up indicator lights are.  Both suggestions of mbworld.

This article deals with the area in the rear where the indicator lights are.  It is detached from the roof by pulling down by the glass, popping a clip on each side with straight downward force.  No pry tool is needed. Then this slides forward to release the part from the ceiling.

Inside you'll find a plastic part that is prone to resonate rattling, by this I mean if you tap it, it sounds hallow and perhaps a bit shaky.  There is a soft noise deadener applied,  carefully remove this part, apply the dynamat beneath it, and reattach the soft noise deadener with the dynamat backing to use as glue against the soft deadener.

I applied dynamat to this plastic part and to the areas that hold the clips in place.  Be careful not to plug the holes though. as their are fingers which slide through these holes.  I added a bit of dynamat above this plastic piece to the bare metal areas.  I tapped on each to see which "rang" or were hallow sounding and applied to those pieces.


3D Printing For Car Enthusiasts

3D printing is a skill right now.  And it may perhaps always remain that way as we push the boundaries of filaments and techniques.  Many of todays prints can be categorized into useful items and trinkets/aesthetic items.  In the field of printing for your car most of the items fit into the former category, perhaps especially for older Mercedes and Land Rovers.

Ender 5 Printing a Oil Filter Socket

Off of thingiverse you can find many useful items ready to print.  Including oil filter sockets, clock parts, push fitment pieces, and more.  Please find a few of the more useful items below (USE AT YOUR OWN RISK):

  1. COMMAND Wheel Axis
  2. Panel Clips
  3. Potentially Front tow hook license plate holder
      2. Car Jack Adapter
  4. Fuseholders
  5. Somethings that might be good for older or classic MB
    1. Sun Visor Clip
    2. Digital Speedometer Gearing


There are also various toys and games to keep you and/or your kids busy.   Of course you can design your own parts with a 3D design tool, or upgrade/modify old ones with a 3D scanner.


DIY Stereo

Eliminate Some Rattling from Rear Deck

Many Mercedes in the USA have a built in subwoofer in the rear deck. There is unfortunately a certain amount of rattle that occurs when the bass or volume is turned up.

I find this unpleasant, and go to great lengths to eliminate rattles. I've researched this a bit, and it seems some are caused by loose nuts in the trunk, some are from areas where the rear shade retracts. I found though a lot comes from the grill that goes over the subwoofer.

It's very easy to take out. Just a few tabs. It's a long piece of plastic with not much holding the tabs in place. I used dynamat on the back of all the tabs and along some of the longer areas without any musical output and along some of the sides.

It's a really nice DIY project that pays big dividends! I would also doubt they would even attempt to fix this at most MB dealerships.

Air Intake DIY Maintenance Performance

Add An Oil Collector

Adding an oil collector on a direct injection engine can help maintain horsepower and mitigate issues with carbon build up on valves.

I first heard of them reading a online forum "discussion" between two tuners and one brings up GAD tuning.  One thing I realized there are tuners that I need to study and post a section about, like GAD and Masonry.

As I studied the build pages GAD mentions an oil separator and now I'm down that rabbit hole.   Well one of my favorite channels EngineeringExplained went into it and tested them.  TLDR they do work and you may want a bigger one (or an AOS) so it doesn't overflow which might be worse than not having one at all.

Adding an Oil Collector is a fairly inexpensive way to protect your Mercedes.  Just like the blow off valves, lower temp thermostat, this won't actually make your car go faster over a new engine, it will just protect your engine and maintain your performance better.  As it is assumed the carbon build up from DI can lower horse power.  Diverting oil into an oil collector can or an air oil separator oil from going back into the crankcase.

Air Oil Separators are Different than Oil Catch Cans

The oil catch can you have to monitor and empty but the air oil separator takes the same goal but a different operation. In the air oil separator there are baffles to separate the oil and air. The oil is put back into the oil system, the air back to the intake.  This system in the video also uses a coolant system which will help the oil apparently not cake (according to the video).



DIY Maintenance

Change Mercedes Wiper Blades

Changing wiper blades, has been best described as something to do often.  Once a year or so.  This cuts down on chatter and improves their efficacy.  Consumer Reports found changing your wiper blades more often is more important than buying the best wiper blades "once".

This soft rubber is often exposed to elements with force and tasked to clean them.  Sun, rain, washer fluid, bird shit, your wiper blades take a beating.  Mercedes built their wiper blade system ingeniously. Incredibly quick to change.

One circular pin and a catch.  You raise the wiper blade, rotate it on its axis (not against the motor) and the wiper blade pulls away.  Installation is the same but reversed.


DIY Maintenance

Change Mercedes Ignition Coil

Changing a coil is a DIY job.  You will need a 17mm open ended wrench or EWK boot removal tool.  Take the 17mm tool and unplug the coil to be replaced.

Remove the airboxes and tubes. Remove the plastic things by pulling up.

Undo the torx (1 is often female torx/ etorx) attaching the specific ignition coil.  Using the same tool apply pressure on the boot downward to index, then outward to remove the boot and coil. Smooth steady pressure outward.  The coil/boot will then pop-off.

Take the new coil and boot assembly and apply the dielectric grease on the boot.  There does seem to be a bit on there anyway, but it is never a bad idea and STAR says to do it to avoid damage to the boot upon removal.

Place the ignition coil back the same way.  Ensure the boot is fully on.  Tighten the star bolt to 6.67 #.  Put the electrical connector back on.  Here is a longer write up on how to change spark plugs which may be helpful as well.



DIY Maintenance

Tuned? Change Your Mercedes Oil More Often

If there is one thing you can count on, people have differing opinions.  A precursory glance at almost any internet forum regarding oil change tactics, oil theory and how it relates to oil weight, oil change interval.

Most people I've come across believe the Mercedes 4.6 M278 M157 and M177 & similar can handle 100-200hp more with bolt ons, not even necessarily all of them. I personally have not seen a completely built m157 with methanol, bigger or billet turbos, dp etc.  Usually people just do a few DP and a Tune stage 2 is most popular.

Getting back to the subject, the one guy I found, after hours of internet forums, facebook, etc, who didn't think the engines should be pushed past stock.  When I pressed a bit he mentioned that the oil should be changed more often when tuned.  I pressed a bit more, he mentioned that tuning did put stress on the timing gear and earlier engine revisions may have weaker timing components.  And stated again the oil needs to be changed more often on a tuned Mercedes.  He said every 3,000 miles.

3000 miles, that is and old school interval.  Or perhaps one for someone who wants to protect their car and get the best out of it.

Approaching 5000 miles I quickly put this video together about how to change your oil as a general DIY guide using the newer suction techniques which these engines were designed in mind for.

Don't let the suction scare you away though.  It takes less time to change the oil on many modern Mercedes than it takes to lift a camry in the air enough to get the oil filter under it.  I would guess 7-10 minutes is a realistic estimate, with people being able to do it in 3-5 with a compressor to drive the suction.

DIY Electronics Maintenance Performance

Change Mercedes Spark Plugs: Tuning? Go for Newer, Colder Spark Plugs

Spark plugs actually have a temperature range that they are designed to operate in.  A colder spark plug doesn't fire colder, but it does help evacuate heat from the cylinder head faster.  Pressures with emissions and finding the right balance between a spark plug that will burn fuel completely even during short trips and one that can handle long hard driving is difficult.

Merecedes over time has revised spark plugs to one step colder on M278 and M157 according to Jason at OE Tuning.  Who recommends the current Mercedes spark plugs with oem gapping for the M278 and M157 even when tuned. NGK and Weistec do offer spark plugs which are colder I believe and some tuners may recommend changing the gap on either setup.

When tuners started with these engines they almost all suggested one step colder plugs.  Over time revisions occurred, and even official power output numbers revised.  This is an important step in your pre-tune checklist.

Changing Mercedes spark plugs are a DIY job but harder than normal.  With a DIY scale of 5-6.  It takes time, you have to go slowly and may not finish in one go.   After changing sparks you'll notice the ECU recalibrating and after this recalibration you may want to consider flashing to a tune if you have had previous trouble.

How to Change Mercedes Spark Plugs

  1. Get the instructions from Mercedes Star
    1. Ask, Search on FB, MBworld as needed
  2. Note the torque and special tools suggested
    1. Buy generic versions of the special tools
  3. Undo electrics with tool
  4. Unscrew two bolts per coil
    1. Unclip any electrical from fuel rod
    2. Unscrew wire harness between cylinder banks
  5. Remove coil with special tool
  6. Remove Spark Plug with special tool
  7. Add antiseize to threads optionally
  8. Add dielectric boot grease to end of boot and spark plug boot area
  9. Put spark plug in spark plug socket, tigheten to specifications, in the case of m278 17 pound feet, approximately tight plus a quarter turn.
  10. Insert boot back on
  11. Plug in coil
  12. Repeat

Fuel injectors have also been revised overtime as I understand for the M278 application.  Some I believe some upgrade these as well.  I'll do more research on the fuel injectors.

DIY Electronics Maintenance Performance

When, Why & How to Replace Mercedes Auxiliary Battery

As the push for ever increasing fuel economy has pushed engines to be more efficient and use innovative technology we may not otherwise see, there are some configurations of Mercedes that run a dual battery set-up with one battery primarily, to my knowledge, to power start the engine and power most things, and another for start stop system reserve and to regulate voltage.  To see how to change the main battery check out this post.

Modern Mercedes use so much computing in the delivery of torque to the wheels, and in almost every sensor, computer, etc.  I figured taking a lesson from Range Rover Ownership that these cars may be sensitive to voltage and I could not be more right. Right out of the gate previously my brakes felt more powerful and confident with the big H8 battery.  With this smaller Aux battery in my car, a 200 CCA Duralast Platinum replacing a 7 year old OEM battery, I wondered what the impact would be.

If you are on a factory battery in years 5-7 you may want to preemptively change your battery without even testing it.  It drives that much better.

In a empty stretch of road I gently hit the gas to a known level.  And wow, she took off.  There was such a big difference I changed the plans for the rest of my day.  Literally, not just taking the long way home, but hey let's drive that beautiful back road to the UPS Store to send the cable equipment back.  Then let's return the core even though this new one isn't even an exact fit.

Wow, completely different.  So different the transmission really had to remap itself in eco pro or whatever, e mode stands for. A CLA 250 was driving very hard stop light to stop light and in eco with almost no effort I outpaced it but she was a bit jerky as the transmission learned.  Perhaps the transmission control unit (TCU) itself was operating differently with the additional torque.  Either way she put down power very nicely.

This drive was so nice. It really made ,e reflect on the fact that with ESP mode on there is a giant barrier of computer between the go pedal and the drivetrain.  I would not recommend running an ECU tune with ESP off.

When to Replace Your Auxiliary Battery

  • It says to
    • There can be a dash warning "Replace Aux Battery". It is ok to drive for a bit but not too long.
  • Your car is a certain age
    • I love the 2014-2016 Mercedes but if you are running original OEM AUX battery you may want to switch it.
  • It doesn't test to rated power
  • Start/Stop Stops Stopping the Engine
    • If your eco is always yellow, and your car isn't staying off as long or as often as it used to, it is a good sign your AUX battery is worn
  • Park Assist Stops Assisting
    • When you pull next to an open spot to parallel park, your car may have previously asked if you want to engage Park assist or something similar
      • If this stops working as often you may want to consider replacing your AUX battery

Why Replace Your Aux Battery

  • You're about to tune your car and the batteries are more than 5 years old
    • For me my car runs better tuned with the batteries updated
      • I would guess it has to do with voltage droop under load while trying to deal with aging batteries as part of the load
  • You want your park assist to assist, and your eco mode to stop your car
  • Overall you like your cars in top operating condition
    • Changing a worn AUX battery does make a palpable difference in my case, and for many reported on MBforums.
Tubing setup aftermarket AUX battery replacement
Here you can see my use of a cut down jura milk frothing adapter and the milk container adapter to connect to the factory tubing.  Using this Upgrade Provides an additional 10% capacity over factory, also using the part compatible AMG battery will yield similar gains. 

How to Replace Your Aux Battery

  • These batteries are often located in the trunk of your car or under the dashboard
    • For ones in the dash I cannot advise further but to point you to MBworld and suggest you ask there, which is not a bad choice when posed with a Mercedes question
  • For the ones located in the boot
    • Fairly easy, a 10mm wrench unhook the terminals
      • I loosely taped positive out of an abundance of caution
      • A 10mm bolt that secures a swinging holder in the case of the C218 likely W212 and similar
      • Unhook the vent
      • Install new battery
        • If you are using an aftermarket battery you will likely need to hold the aftermarket bolt loosely with your hand
        • If you are using aftermarket consider the venting solution if it doesn't fit stock
          • I ended up using two tips from a JURA Espresso Machine Milk hook up
            • I cut the black frothing tip down and used the tubing to connect while using the clear tip to connect to the factory tubing

Upgrade Mercedes Battery

  • AUX 14, and various 14 size batteries will work
    • Some car audio batteries may fit, these are hybrid batteries designed with large capacitors to capture and deliver power faster
    • You will likely need to modify the vent system or holding system in some cases.
  • AUX 14 Platinum
    • Will likely need to utilize vent adapter as above, and hold the bolts in
  • AMG Batteries are often bigger than non-AMG but will direct fit
    • CLS 63 battery almost surely fits perfectly into the CLS550 and provides ~12% increase in CCA from 170 to 200.

Ease of DIY: 1 for MB Battery 4 for non-MB battery

You will need a 10mm wrench or socket.  No extenders are needed.   If you are going to a different battery other than MB, may need to fabricate a vent adapter as above out of a cut down Jura milk adapter.

DIY ECU Tuning Electronics Maintenance Performance

Upgrade Mercedes-Benz Main Battery

I've often read the term pre-tune checklist on various posts across facebook groups, forums, etc.  One of the items that you may want to consider is replacing your Mercedes battery, regardless of how it tests if it is over six years old. There are two batteries on many late model Mercedes.  This article is about changing the main battery, if you would like to see more about changing the auxiliary battery on a Mercedes, please see here.

DIY Ease Score 2-3

(out of 10 being like a re-timing/transmission rebuild, something possible but perhaps hard for DIY)

Tools Needed

10mm socket plus 6 inch plus extension.

Why Replace a Good Old Battery?

Replacing your an older Mercedes Verta battery is important for many reason I don't understand.  However, in general modern cars use a lot of electrical load for the amount of voltage they were designed for and they are very sensitive to having a working voltage that they like.  And while they may crank and run a variety of mercedes elecrtical sub systems may not work optimally if the presented voltage is on the low side of what is anticipated.  If the alternator is struggling to charge an older battery it is entirely possible that under the increased stress of a tune may present errors with injectors and spark plugs as well as ECU and TCU, etc.

What did I just write?

On my range rovers lots of weird little electrical gremlins were actually the beginning of being able to tell a battery was going.  And it is still true today.  Often things like the radio may not seem to have as much head room, or perhaps brakes feel squashy, HOLD doesn't engage as well.  Things like that.


H8 Upgraded Battery Size installed into a Mercedes C218. >10% Increased Capacity


Updating the battery isn't very difficult.  You will most likely need a 6" extension, a 10mm socket and a 13mm socket as well as a towel.

The battery slots in one direction which needs to be matched.  The batteries themselves are slightly heavier than expected.  Make sure your hood is open beyond the normal opening, but to the often available on Mercedes, service opening straight up position.

My car felt better right away.  For example changing the battery provided a

Brake Boost

Updating a battery, for whatever reason, in my car made the brakes feel much tighter with more consistent pedal feel, earlier.

This is just an example I would guess of the change of running on a 7 year old battery to hopefully something newer.