Mercedes-Benz W205 Auxiliary Battery Replacement DIY (Mercedes-Benz C300, S63 AMG, C63 AMG, & More)

[@garyvanremortel5218]

Super concise format, well presented. No crappy music to detract from the content. IMO you guys are the Gold Standard for KZbin repair videos.

[@fcpeuro]

We really appreciate that Gary, we are constantly trying to improve our DIY videos and format, glad youre enjoying them.

[@Nohndl]

This has got to be the most thorough and professional service example I have seen. I appreciated details like tools needed, lighting, and even cautionary examples like making sure not to lose parts or damage the interior - even how to keep the frustrating carpet out of the way. Great team job.

[@1mpost0r]

Great video, this is how the DIY tutorials should be done! No useless music, list of tools upfront, good angles, straight to the point. Thanks! I have used this video to replace the aux battery on C200 wagon - it was slightly different, but this video gives you more than enough information to get it done. The main differences: - the panel with T15 screw has only single screw and two clips - the footwell panel was held by three nuts - two on the bottom, one on the top left (UK version) - all of the nuts are 10mm (panels and the battery), no need for 8mm The most difficult part of the repair was bending/pulling back the carpet as it was very stiff.

[@fcpeuro]

Thank you for the first hand feedback!

[@cforrester2186]

Great to-the-point video! You have saved me the outrageous MB dealer fees to have this done. Bought the part and it only took me 30-45 minutes to do replace on my GLC300 start to finish.

[@fcpeuro]

Great to hear! It is wild what they can charge for a job like this one.

[@joshmills955]

Just done mine. I'm a complete novice with anything like this. Brilliant video! Saved me a fortune thank you.

[@rockviewvideo8049]

I was a grease monkey rebuilding hot-rods all through high school. However, that was in the '70's and cars nowadays are very daunting with what is perceived as "complicated" electronics. But your videos really make the complicated simple. I completed this replacement in less than 30 minutes and so far, so good. Also, it's one thing to know WHAT to do, but it's another thing alltogether to know that it CAN be done. That was the biggest hurdle for me. Thank You!!!

[@tattooedfoodbeast6755]

Perfect video. Easy to follow, and until this video was posted I couldn’t find decent instructions for this super easy swap. Thank you!

[@jamesriley5057]

Agreed. I watched a related video where the guy drops the 8mm screw down in that gap under the rug and turns this simple job into a tedious one real fast.

[@Analogkid299]

Excellent tutorial Kyle!! I was a MBZ Factory Trained Master Technician and Trainer back in the ‘80’s and mid-nineties, then moved in another direction and spent 20 more years in MBZ Sales Management. I checked out your video, as my wife’s 2018 C300 just got the “Pull over and leave the car running…” error message. Obviously I haven’t “turned wrenches” in awhile, so that led me to your video. I actually have a MBZ Extended Warranty on the vehicle, so it should be covered under warranty, but I always like to know what’s going on. In any event, being a former MBZ Technician/Trainer myself, I can tell you are a very conscientious and quality technician! You do clean work and your explanations and thoroughness are “top shelf!” I would have no reservations recommending you as a technician! Thanks again for the great video! 👍🏼

[@ooguiile]

This was HELLA useful for me and my C63s 👍🏻. Although the aux batt was not burnt, the fuse was blown. So I replaced both and voilà.

[@DEJF90]

I'm awful at DIY, but even i managed to follow this. Superb instructions, really easy to follow. Thank you so much!

[@zuluwarrior791]

Excellent instructional videos, well done Kyle, clear, logical and just the right level of advice and guidance needed for a successful task completion. As said previously these are the Gold Standard for YT MB repair videos.

[@miketoft8168]

Most useful video. Clear and easy to follow. Putting the trim and carpet back was a bit fiddly, but quick and easy even for an amateur like me. It didn't even matter that you've got the steering wheel on the wrong side 😂

[@windsofhealth]

I just replaced mine using this vid as a guide. Took a bit longer than you did but nothing broken and everything looks like it did before the installation. Saved money on service fees and Aux Batt Malfunction message is gone!! Thanks a lot. The video is much appreciated.

[@nathanbryant45]

Thank you so much for a clear & thorough video, was easy to swap the Aux battery with your help. Very professional video 😊

[@arosle2560]

Thank you! I had the capacitor changed 3x times! But the error message was still there. Drove the car for the past 3 years with the error message visible until I saw this. This is the only video that mentioned to check in the fuse in the trunk. And guess what? My fuse were blown this whole time. Bought new 10A fuse and magically error meesage gone! Thank you so much for your help!!!

[@79jaimes]

Muchas gracias!! me ha ayudado con el problema de la batería de mi coche, dos talleres automotrices no pudieron dar con el problema, y gracias a este video lo pude arreglar yo mismo sin tener conocimientos al respecto. Mil gracias !!

[@markerwin2672]

Done. I purchased the part online and took my laptop in my C300. You walked me through every step. Well done! You saved me a ton of money. BTW, The nut retaining the Aux. was a 10mm, not an 8mm.

[@fcpeuro]

Love to hear it, thank you for the note!

[@BassGods]

Is this the same location for a 2016 C300?

[@christopheraden4035]

@@BassGods yes!

[@BassGods]

@@christopheraden4035 Thanks! Replaced!

[@sivbum960]

Excellent, the special tools photo of the items needed is a beautiful idea for DIY audience. THANK YOU!

[@coffeeman2079]

Thank you for this excellent video. The car calling it an Auxiliary Battery threw me initially but after hours of searching found that it was the a Voltage Converter. This lead to your video. Mercedes were going to charge me £150 for a diagnostic (what’s the point of the on board computer telling you exactly what’s wrong🙄) and then whatever the Converter cost and fitting was . Two separate visits and inconvenience not having car. The online search was well worth the time and coffee drinking. Now to get it fitted. You made it look fairly straightforward 👍

[@christopherneff7846]

Excellent Video - agree with the other comments - it took me longer to drive to the jobber to get the part than it did to restore the "auxiliary battery malfunction" and test drive. From tools required to the full, concise, logical, and informative presentation. I went back to review removing the wire from the old regulator and aligning the plastic panel that holds the pax light and interior temp sensor and still beat my 40 minute drive time. If you know anything about resetting a 2003 VW European clock spring - I'd love to see a video. Great Job Kyle.

[@chrispiscopo4631]

Thanks very much Kyle. I noticed a couple of small differences with my car which is a right hand drive australian model 2016 c300. The bolt holding my converter was 10mm not 8mm, and I had no second T15 screw holding the upper plastic panel - not missing, just not designed for it. A couple of extra notes to assist with aligning the plastic panels, the upper panel needs to align with an air vent - when I focused on that the panel moved in to place perfectly. Second, the side panel not only has to align with that white arm near the fuse box but also a couple of latches on the side near the door opening. Once I got that the panel sat right against the side.

[@salesmanager8377]

great vido: do youknow if it on the Left or right side for RHD ( Australia) drive?

[@Harrybollox]

Thanks this worked superbly in my RHD wagon. Only one screw on the first panel, and all three bolts 10mm .

[@indianboi3]

Thank you so much bro, just got this done on my 2015 C300 W205. Initially the error I had didn't go away but after a couple of drives the error for "shift to P, leave engine running" finally went away 🙏

[@AirgunNinja]

Thank you for posting this very helpful video! The only difference in my 2016 c300, the nut for the capacitor is also a 10mm not an 8mm. Everything else was exactly the same. I, too, can tell someone was under the panels. It was missing one T15 screw and the little hook arm under the top panel was ganked. Again, thank you!

[@1940tony]

m

[@pyourpane]

Did this help? I too have a 2016 c300. Same message on the instrument cluster. I’ve had to replace the alternator and battery.

[@BassGods]

I have same car. Is it the same location as the video?

[@johntaylor4057]

Superb presentation. Just the way I like it. Everything described 'A to Z' very well done, many thanks.

[@keithr.santillo4559]

Kyle...Great demo... How do you reset the Warning after changing the parking pole capacitor..

[@billmcquitty719]

Very clear instructions. changed out auxiliary battery but warning still on dash. Any ideas.Thanks

[@shaileshakhouri5385]

This helped me save dealership fee. Awesome instructions for each step. Thanks

[@fcpeuro]

Great to hear!

[@George-ww9ob]

Great presentation thanks 👍🏼 my start stop feature on my c300 coupe 2017 works once in a while only and i didn’t get any message on the dash most likely its from the auxiliary battery. I have my rear defroster not working it turns on for a second and then turns off automatically, do you think it has something to do with auxiliary battery too? Thanks

[@melgreen4979]

Great video, really well informed and easy to understand you. I did the replacement in a GLC and it was almost identical. Small problem was the insulation foam cracked quite a bit. Thank you!!!

[@fcpeuro]

Glad it helped!

[@openmind6969]

Will attempt my GLC in next days as well. Any note on what was different?

[@melgreen4979]

@@openmind6969 just the carpet was really awkward to pull back as the side piece wouldn't bend. It actually looked like someone was there before as the foam was broken and I made it a bit worse. But it all went back together ok. Remember fuse 448. Good luck!

[@ksauto1]

thanks for the great video, found this just in time as I have customer coming in next week to have this replaced. I did notice you DID NOT fully clip the underdash panel back together-one of the 2 clips was not pushed back in on the left side!

[@fatboylousa6247]

Thank you very much, I was able to replace it on my E300 without incident thanks to your explanation. No more annoying Aux Batt Maulfuction message... Thanks!!!

[@robertarce7272]

Great video, To the point, well explained. I had the warning come up and was able to repair the problem myself following your video instructions. I wonder how much the dealer would have charge me to repair it? Thank you very much for your great video.

[@willr3877]

Just got quoted $390 at an Indy…

[@maxkondratyuk99]

Did the code disappear on it ls own after you replaced it? I replaced mine and the code still pops up I’m not sure what the problem is

[@MJMAMA12]

@@maxkondratyuk99did you ever figure it out? Was the fuse blown?

[@maxkondratyuk99]

@@MJMAMA12 it ended up being my main battery even though I got the same warning as the auxiliary. Kinda strange

[@WilliamLowery-v3i]

Job well done. Straight to the point with very much understanding

[@domenicdambrosio1465]

you could of not been more clear and to point. Thank you so much!

[@ssfutube]

Outstanding clear concise presentation. You are the best. Thank you.

[@jorgezuniga7777]

Excellent Video & very professional. Now we clear how to replace the aux. battery. Thanks much...

[@krupin12]

Dear Sir, thank you for this guide. Just did the replacement in my coupe, 20 min. of work.

[@gagangowda6600]

Hey Aleksander, did u replace it for a c300 coupe 2017 ?

[@krupin12]

@@gagangowda6600 Hi, nope, I did it in 2016 C43 coupé

[@kaneda4102]

Legend- you just saved me hundreds by following this. Thank you for this excellent video.

[@fcpeuro]

Nice work!

[@philandrews9216]

Excellent video, clear,precise but not over complicated. Thanks for sharing. Phil.

[@fcpeuro]

Thank you for watching!

[@osama692110]

Thank you the best auto repair video I have ever seen

[@MrEjoeb7]

Where is the MAP sensor located for a Mercedez C300 4MATIC. I been trying to change it and can't seem to find any guidance. could you do a Vido on this? Thank you for your videos. very educational and clear to follow

[@suzy6005]

Awesome! Good clear instructions well explained. I have a UK GLC 250D (2016) same location and part, plastic a bit fiddly to refit but saved £££ on both the part and fitting so well worth it. Many thanks.

[@abesolano7744]

great video!! ordered the part from the dealership and did it myself before watching this video.. only problem was after it was installed, I am still getting the error code. this video exactly showed me what I missed which was checking the fuze box.. if I fix the fuze would that solve the error messages still?

[@Missautumnashley]

Omg thank you so much for this vid!!! I did ittttt by myself !!! Well with God and your vid 🙌🏽🙌🏽🙌🏽🙌🏽🙌🏽🙌🏽🙌🏽

[@mixxedjustright]

This was excellent. Super easy, thanks for walking me through this.

[@xiome3145]

Hello Kyle, great video, my 2017 C300 use a T 20 torx and no need for the 8 mm, for the floor panel with the 3 nuts size 10 mm i took a piece of plastic put over the end of the socket and that will help for the nut to stay wedged in the socket. Thanks

[@dr.enricobarberis5949]

Congratulation! Easy for you as you show but for me is mission impossible😂😂😂 Many thanks! Enrico

[@Plattlane70]

Love your channel quick question does the auxiliary battery effect keyless entry at all. I changed all the fuses but keyless entry still not working. Pain using master key to enter in and out of the w205

[@Doctorj63]

Very good video. Also a great time to replace your cabin air filter.

[@channelwhywhywhy]

Absolutely perfect! Thank you! Just about to replace mine now.

[@TwinSted666]

Great video and exactly to the point!Yesterday i've got the message on my dashboard saying that with red text "auxiliary battery malfunction" then after 1 min the message just appeared on white. Today i changed my aux battery and the message still appears with white then i've check on the trunk and find also my fuse 10N was burnt out. After i changed the fuse the message disappeared. Regarding this i have two questions..is there any chance to get the message about aux battery just because the fuse failed? Also when i changed the fuse it was 10N but i couldn't find the same one so i've got just a fuse 10 standard i belive it is. It's there any problem because it's not the same like 10N?

[@jh9493]

First class instructions!! Just fitted this part to my car 😊 Thanks 👍

[@rareyes3604]

Great video - any tips for removing a stripped T15 screw? I tried to remove the first screw under the passenger side and discovered it was stripped.

[@zdenekmasek9643]

Hi, nice video. What type of connector on cable harness side is used? Some number has to be printed on it. Thank you.

[@ghalibalogaily460]

After replacing the auxiliary battery. Should erase the fault code by scanner..thanks

[@Alex-dk9hu]

Can you provide a link where this part can be ordered at FCP Euro? Thankyou this video was very helpful.

[@brownsbikingadventures5679]

Hi great video, I have a c220d 2016 but it's not at that location on the video. Any idea where it could be located? Need help plz

[@tomwander2804]

First class video. Keep up the great work!

[@BillGolden-g6x]

Great video. I replaced mine (2019 C300) easily with your instructions, but my start/stop and a few other things are still not working. They will start working once the car has warmed up for a while. Any suggestions?

[@JonathanPersaudx]

Did you replace the main H7 AGM battery? Normally replacing both will fix that unless it detects a fault with the starter

[@whyzeep3778]

Very nice instructions! Great job. Now, I feel comfortable getting started.

[@kevinlavender6736]

Do you need to disconnect the main battery before doing the work on the aux battery?

[@Gavolak]

My Mercedes dealership wants to charge $500 to get this fixed, but my rep there did stress that it’s not worth it and that on my car, my systems are fine and the electricals aren’t going to crap out on me. However, the warning message keeps coming on. It’s been a little over a month of the warning message. Should I replace the battery just to stop the message from popping up?

[@SwiftHDX]

Excellent tutorial, I'm starting to get annoyed by the error message so after watching your video I was confident enough to order the part and I will be doing the replacement myself. Easily saves me a few hundred bucks. Thank you.

[@fcpeuro]

You got this!

[@shaygavrieloff7850]

Thank you for your video you helped me to save $400

[@fizzysausage]

Super helpful, clear and well presented, thank you!!

[@simonlefter4824]

Thx to you I was able to changed on my self and save a lot of money! Great job guys keep going!

[@ericramirez8301]

Just installed stalled mine quick and easy thanks for the awesome video I just now need to clear the "stop vehicle code "

[@fcpeuro]

Nice!

[@Aaron40117]

Brilliant! thanks so much for providing a detailed guide on this.

[@Justsomeguy1015]

Did this to my dad 2015 c300 when it hit 50k miles. It comes out of nowhere and you get an auxiliary battery warning. Was not hard to do prob took me an hour and that was from looking at schematics of where it was placed. Would recommend you to disconnect the main battery when working with stuff like this.

[@thewiseguy7100]

Same with mine, randomly get Auxiliary Battery malfunction.

[@DonnaInMalibu]

I wish I followed this video first. I watched other tutorials and ended up breaking like 5 clips because people don't know what they're talking about. Onlyt things I'd mention is that aty 2:31 you mention there should be two T15 screws holding the panel in place. Actually if you don't have the knee-airbag there, it is only ONE screw. You don't have the knee-airbag on that side there, so it is correct that there was only one screw.

[@nnesander]

Hi, thank you for the video, it’s really helpful! My car is C180 model year 2019, what’s the part number of this element? I couldn’t find it in the provided site. Appreciate your help. Thank you

[@fcpeuro]

Hi there nneskander! You can sometimes find the auxiliary battery referred to as a "Voltage Converter." Try searching the part number 205905341480 on our site!

[@yawnerddn]

This video was really helpful and gave me the confidence to perform this task myself. I would have appreciated slightly more detail on how to disconnect the actual 3 pin connector on the voltage converter. I struggled with that until ringing a mechanic friend for advice ! 🤣

[@fcpeuro]

Glad, to be of some help, thank you for the note!

[@umchpetrol]

What a concise accurate video. Thanks very much!

[@TheMstrv]

does the same process apply to the Coupe version? i have a 2017 c300 coupe, want to make sure I do the right thing )

[@fcpeuro]

Hi Victor, same idea for your Coupe! Best to inspect the working area first before starting your repair so you are comfortable with it.

[@angeltorres7936]

Is there any testing that needs to be done or is replacing the auxiliary battery essentially just plug and play?

[@seyedziaeddinkanani2735]

Great video. Well explained with all the details. Thank you.

[@lelyakursanova4444]

Great video I have that problem ,ordered the part from you guys and replaced it with your help it was such an easy job however the problem still there, as soon as I started the car the message showed up.

[@arosle2560]

Check the fuse in the trunk as he mentioned in the last part :)

[@masterp1816]

Maybe your main battery is dead

[@willclarkfinancial]

Just replaced it using this awesome guide but I’m still getting auxiliary battery malfunction error message. Do I need to reset it somehow?

[@alperakdag9764]

Great Video, thank you! In the video, it was mentioned that for a C-Class Hybrid Model, size 14 auxiliary battery is used instead of the „voltage regulator“ and that needs to replaced. Can this auxiliary battery be found in the same location as well, or assembled at a different location?

[@michaelgillan380]

@alperakdag9764 did you get an answer or find out about your hybrid model was the location the same?

[@mohammedabdulrahman2390]

Thanks for easing procedures. With s350, don't we have to disconnect the main battery before proceeding to replace the auxiliary one?

[@yawnerddn]

I didn’t !

[@calimerosdaily]

Hi, I own a Mercedes w205 c350e. I understand that the type of battery is different but is the location the same? Thanks for your reply, it will help me a lot.

[@fcpeuro]

If you need any assistance with this, please email our team over at [e-mail]!

[@GeorgiaMade404]

What about when the battery is located under the rear seat? Can’t find how to access this anywhere online. It’s like mines is the only one with a back seat battery. Smh…no more Mercedes for me!

[@antoinewatts96]

Can you do a video for a 2017 Mercedes Benz alternator

[@bohjeresen]

Thank you very much for an informative and clear video instruction, I have just completed the task and I was grateful that I could see through all the processes in the task. 😃

[@matthewbrown33]

You're the man Kyle - very good video ;)

[@jonjones6749]

Can you tell me what the Auxiliary battery controls? Can it start to go bad and not show an error message? Does the regular battery charge the Aux. battery or only the alternator charges Aux. battery?

[@bighonchox6698]

THANK YOU SO MUCH YOU GUYS ARE LIFE SAVERS !! I have the same car but a 2017

[@rareyes3604]

Did you have a problem removing the T15 screw? I have a 2017 also....

[@bighonchox6698]

@@rareyes3604 well I haven’t started it yet because I’m going to order the part next week and get the tools that I need to do this myself. I will have one of my friends with me to help me if I need assistance. So I definitely will let you know how it goes next week or in 2 weeks stay tuned.

[@ads998]

Odd question, being in Australia, I'm wondering if this is still located on the right side of the car which is the driver's side in my case?

[@fcpeuro]

Hmmm, let us know what you find!

[@harryhomer4818]

Would this capacitor in the video and install video be applicable to a C220 Mercedes 2015 ? I have the auxiliary battery malunction showing but the cars not listed? Thanks

[@DR-GH]

Thank you for your informative video. I want to ask you about a problem we are having in E300 (W213) 2018. The parking pilot and hold function sometimes work and sometimes not. We changed both the auxiliary battery and main battery and after the changes they work but in the next day the problem comes back. The dealership was of no help. They had the car for around 10 days and cost around $800 and they are not sure of the cause!

[@205.BRABUS]

Did you ever find out what was wrong?

[@renepeirano6120]

Does this auxillary battery have any relation to no sound coming out of speakers?

[@petersepulvedajr5786]

Would think affect Bluetooth ? I had this code pop up to replace then it went away like 2 days later and my Bluetooth won’t work anymore I have a 16’ w205 thanks .

[@fcpeuro]

Hi Peter, the aux battery should not affect Bluetooth. Scanning the system would be the next best move to see if the module throws any codes, and go from there.

[@edward1927]

Is there any way to test the auxiliary battery before replacement? I have access to an Autel. Edit: Found in the EIS/EZS module, live data shows voltages of power supply (main battery) and additional battery (aux battery) RSAM fuse pointed out in video was good, additional battery voltage showed 0 implying the capacitor in it is no good.

[@tyronefinkley9090]

Good job with presentation. Thanks for your help, and God bless you

[@twinpyramidshoney543]

I have the hybrid model but cannot seem to find the auxiliary battery. Where can one find it? 2017 c350e thank you a ton

[@xb00m3rangx3]

I’m assuming since swapping this part didn’t make the light go out then it’s the main battery?

[@print-master]

Thanks for an excellent video 5* no dumbass music to distract. you are articulate and clear cut. Many thanks

[@Iustin.A]

Wait a minute. So the piece made by Hella is the exact same you get when purchasing from Mercedes?