RennTech ECU Tune
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Newbie
Joined: Mar 2016
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From: Boston
Mercedes S63 AMG Coupe
RennTech ECU Tune
Does anybody know it I do a RennTech ECU upgrade to my S63 Coupe if it voids my Mercedes warranty? The dealership says it will void my warranty but I have been researching around and it seems like it does not void the engine warrenty. Has anyone had an experience with this or actually know the real fact behind this? I want to get this ECU tune but worried it will void my warranty
Super Member
Joined: Jul 2012
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From: HESPERIA CA
2011 E550
Warranty will absolutely be voided. Anytime you're deviating from the manufacturers (Mercedes) specs and tolerances, the manufacturer is absolutely allowed to wipe their hands clean and you're alone holding the bag.
Super Member
Joined: Nov 2013
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S63
My local MB dealer is also a Renntech AD (got that from the Renntech site). I emailed the listed rep (MB parts manager) and he replied that it will NOT void the warranty.
The price was $4082, a lil pricier than most, but gives you piece of mind.
The price was $4082, a lil pricier than most, but gives you piece of mind.
Last edited by Manofsteelpt; May 28, 2017 at 08:01 PM.
Super Member
Joined: Nov 2013
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S63
This an exclusion from my MB ELW:
"Damage Due To Alterations: Alterations by changing or adding to the vehicle that adversely affect its performance, reliability, and longevity."
Reading that, I would say that the mod would have to have an ADVERSE effect on the vehicle. Does the tune produce that? Maybe it does, maybe it doesn't, I certainly don't know
but, not "anytime" as you suggested.I will add that my S63 has been in the shop WITH a suspension issue while I had aftermarket lowering links installed, and the car was covered. They even removed and replaced them with OEM (as per my request). Not a tune, but warranty covered despite me having links installed.
Last edited by Manofsteelpt; May 28, 2017 at 08:13 PM.
Super Member
Joined: Dec 2014
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From: Northern NJ
2015 E550 Coupe
While your local dealership may elect to service your vehicle, up to a certain dollar amount before they cut you loose, the manufacturers warranty on your engine from MB will be gone. Obviously non-engine related or drive train issues like lights,COMMAND, cruise control, etc. will still be covered by warranty. MB can detect the deviation in your ECU's code as soon as they hook up your vehicle for diagnostic scan and then your vehicle is automatically flagged by MB corporate.
Super Member
Joined: Nov 2013
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S63
Possibly, but if MB sells and installs the tune, and they state that it doesn't void my warranty, I'm gonna go with that. Legally, they'd be responsible. If not MBUSA, then at the very least the particular MB dealership is. Wouldn't u agree?
Out Of Control!!
Joined: Jun 2004
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2014 E63S; AMS 100 octane ECU dyno tune; EDOK TCU tune; BB intakes; sprintbooster
I would agree that the installing dealer is MOST likely to honor any warranty claims or service because they installed it ... however what did the fine print say? Mbusa is very clear that they will not honor warranty work on modified vehicles and amg Tobias moers states this as well
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Super Member
Joined: Dec 2014
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From: Northern NJ
2015 E550 Coupe
I would agree that the installing dealer is MOST likely to honor any warranty claims or service because they installed it ... however what did the fine print say? Mbusa is very clear that they will not honor warranty work on modified vehicles and amg Tobias moers states this as well
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Super Member
Joined: Dec 2014
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From: Northern NJ
2015 E550 Coupe
Again, that is what Peter and I are saying. Any engine or drivetrain warranty after the tune would be with your local dealership ONLY. MBUSA has made their position very clear for quite a while now. So just read whatever paperwork the dealership has you sign very closely. Again, you need to go into this with your eyes wide open and understand what, if any, exclusions or financial limits exist.
If the dealership is willing to put themselves on the hook for a potentially catastrophic engine failure, resulting in a $25K to $30K or more bill, for the price of a tune then great. Wonderful! We need more MB dealerships with that kind of potentially poor business judgement. That they are willing to roll the dice and back our desire for ever-more power with their wallets. What's not to love? Everybody would be getting tunes and not have a care in the world, because the dealership would be picking up the tab for any problems.
If on the other hand, you read language like you find in many tuner's limited liability warranties, that limit their financial exposure to the value of the tune itself, in your case $4082, then you know where the dealer's financial liability ends and yours begins. Nothing wrong with doing performance mods. Just understand your real potential out of pocket costs going in up front.
If the dealership is willing to put themselves on the hook for a potentially catastrophic engine failure, resulting in a $25K to $30K or more bill, for the price of a tune then great. Wonderful! We need more MB dealerships with that kind of potentially poor business judgement. That they are willing to roll the dice and back our desire for ever-more power with their wallets. What's not to love? Everybody would be getting tunes and not have a care in the world, because the dealership would be picking up the tab for any problems.
If on the other hand, you read language like you find in many tuner's limited liability warranties, that limit their financial exposure to the value of the tune itself, in your case $4082, then you know where the dealer's financial liability ends and yours begins. Nothing wrong with doing performance mods. Just understand your real potential out of pocket costs going in up front.
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Joined: May 2017
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2016 S63 AMG, 2007 S65 AMG
I assumed that any ECU upgrade would void warranty, so I mentally prepped myself for that before I shipped it out lol regardless of what any company says. My local dealership confirmed this notion as well. With that being said, since I am most likely voided anyway, I figured I would research and pick a high powered and quality tune. I ended up shipping my ECU to AMR Performance. They have a great staff with an even greater product. My car is an absolute animal when I want it to be and I love it. Just giving my two cents with upgrade options. I would recommend them 110%
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S, GL
Remember, nothing is accidental or forgotten - dealers say what they need to say to get the sale
Your dealer is backstopping your original but-now-gone OEM powertrain warranty, make sure you have this in explicit writing ... the dealer is basically pushing thru repairs under warranty even though they shouldn't be covered
It is easier for them to state that your warranty isn't voided vs getting into the specifics of well, your OEM warranty is gone but we'll stand behind you since that would cause some customers to rethink spending the money
Dealers say what they need to say to get the sale
But, there's still risk, and I've only seen this once - major AMG engine failure, and there was no way for the dealership to pass it along as a warranty repair since corporate would send a tech to investigate ... so the dealer just shrugged its shoulders and told the customer she would have to pay the $30K repair (even though the customer had it in writing that repairs would be covered)
Why? No dealer is going to spend any significant money out of pocket nor would they risk their relationship with corporate over 1 customer
MBWorld Fanatic!
Joined: Mar 2002
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From: Kenilworth, il usa
GT63S ePerformance 4dr, '25 Bentayga Black Ed.(wife), Wrangler and 250 MLB(kids)
Warranty is not voided unless the MBUSA finds out about it.
Many dealers represent Renntech and keep the fact that some cars are modified to themselves and continue to make warranty claims.
On my circa 16 cars modded with Renntech only one was "caught", SL65 in 2007 and only by accident but received Status 8 immediately.
Brabus on the other hand, never heard of any car modded by them losing warranty.
My 2004 S600 with about $45K of mods by them (all mechanical, none cosmetic) even had a MBUSA tech making an assessment of an electronics problem.
Many dealers represent Renntech and keep the fact that some cars are modified to themselves and continue to make warranty claims.
On my circa 16 cars modded with Renntech only one was "caught", SL65 in 2007 and only by accident but received Status 8 immediately.
Brabus on the other hand, never heard of any car modded by them losing warranty.
My 2004 S600 with about $45K of mods by them (all mechanical, none cosmetic) even had a MBUSA tech making an assessment of an electronics problem.
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Joined: Aug 2011
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CL500
Warranty is not voided unless the MBUSA finds out about it.
Many dealers represent Renntech and keep the fact that some cars are modified to themselves and continue to make warranty claims.
On my circa 16 cars modded with Renntech only one was "caught", SL65 in 2007 and only by accident but received Status 8 immediately.
Brabus on the other hand, never heard of any car modded by them losing warranty.
My 2004 S600 with about $45K of mods by them (all mechanical, none cosmetic) even had a MBUSA tech making an assessment of an electronics problem.
Many dealers represent Renntech and keep the fact that some cars are modified to themselves and continue to make warranty claims.
On my circa 16 cars modded with Renntech only one was "caught", SL65 in 2007 and only by accident but received Status 8 immediately.
Brabus on the other hand, never heard of any car modded by them losing warranty.
My 2004 S600 with about $45K of mods by them (all mechanical, none cosmetic) even had a MBUSA tech making an assessment of an electronics problem.
+1
Junior Member
Joined: May 2011
Posts: 35
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From: Texas
2009 CL 63
In Houston we have 3 MB Dealerships that are Renntech authorized and they all stated that any mods they do wont affect the warranty...I'm having MBOTW work a tune into my deal on new car with 24 miles.
Junior Member
Joined: Sep 2013
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From: NYC
2015 S63 AMG Coupe Edition 1
I had the stage 1 Renntech ECU tune done on my 2014 CLS63 S. The service manager for the dealership is an authorized Renntech dealer and installer and AMG performance center. He specifically told me yes, technically the warranty is void. However, they honor all warranties even if it has the ECU tune as long as it was done at the dealership. On the service records, they wrote Software upgrade and the manager kept note of all vehicles with the tune. If they are an authorized renntech dealer and AMG center, I would most likely say they will honor the warranty as long as they installed the tune. If you go to different dealerships / shops though it might be different.
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Joined: Aug 2011
Posts: 377
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CL500
I had the stage 1 Renntech ECU tune done on my 2014 CLS63 S. The service manager for the dealership is an authorized Renntech dealer and installer and AMG performance center. He specifically told me yes, technically the warranty is void. However, they honor all warranties even if it has the ECU tune as long as it was done at the dealership. On the service records, they wrote Software upgrade and the manager kept note of all vehicles with the tune. If they are an authorized renntech dealer and AMG center, I would most likely say they will honor the warranty as long as they installed the tune. If you go to different dealerships / shops though it might be different.
Super Member
Joined: Jan 2007
Posts: 766
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S, GL
I had the stage 1 Renntech ECU tune done on my 2014 CLS63 S. The service manager for the dealership is an authorized Renntech dealer and installer and AMG performance center. He specifically told me yes, technically the warranty is void. However, they honor all warranties even if it has the ECU tune as long as it was done at the dealership. On the service records, they wrote Software upgrade and the manager kept note of all vehicles with the tune. If they are an authorized renntech dealer and AMG center, I would most likely say they will honor the warranty as long as they installed the tune. If you go to different dealerships / shops though it might be different.
The example I listed above happened in the NY area even after the dealer said he'd be covered
Junior Member
Joined: Sep 2013
Posts: 30
Likes: 3
From: NYC
2015 S63 AMG Coupe Edition 1
Good to know! However, I sold that car a few months back and only had a few battery and mbrace problems that were warranty related. I'm sure if something major were to happen like the situation you described it would be a big hassle. I have an S63 and was considering another tune but might do it down the road and get an extended warranty beforehand if I do.
