AMGeez

I have a CPO car and don't want to risk the warranty. Can they tell if you have an ECU mod? Also, would they reflash the ECU during a service event thus wiping out the pricey mod?

CZ55

They can detect if it's tuned. You need to tell them not to re-flash your ECU. Although most likely they won't re-flash it but there is a possibility.

DuaneC63

Yes they can tell because the ECU has to be taken out and opened to flash a C63. Kiss your CPO drivetrain warranty goodbye.

Merc63

They wont just reflash your ECU because you took it for a service. Its a 2-3 hour job at the dealer to flash an ECU and they don't look at them unless they are very suspicious or you gave them a hint or reason to look at it.

If you are worried about warranty, get a secondary ECU for your tune and keep the stock unit.

Vegas_AMG

This part I still don't understand. You have to order it from THEM and take to them to mate it to your car? Doesn't that raise more suspicion?

Merc63

Ya but how can they prove that you actually went and got a tune and used it???

All you have to say is that you bought the ECU, had second thoughts and its been sitting at home ever since.

Or take it to another dealer who you don't regularly go to.


I am doing his exact process and have never had any problems. Just had the car in there for warranty work and its going back tomorrow to have a left bank lean and cam tensioner repaired tomorrow.

DuaneC63

I like the concept but how much does another ECU cost with installation. Is the swap between the tuned ECU and new "stock ECU" a DIY plug and play.

Merc63

ECU cost around 2k then about 300 bucks to program it to the car. You can honestly swap them in under 2minutes with zero tools, they pop right out.

Once my warranty is done I will inquire if its possible to re-write over it for a new car as I will have no need for 2 ECUs then.. (Warranty up in about 7 months)

Even Money

Don't buy 2 ecu just to try and fool the dealer. Your relationship with them shouldn't be adversarial. Find a dealer that's acceptable, some even sell Kleeman tunes.

Nanoflex

January 2012 - Renntech were very helpful and confirmed that you may have only ONE ECU per vehicle.

They did not elaborate, although I speculate the alarm system is encoded for a specific vehicle/ECU match.

If the dealership flashes the modified ECU, Renntech WILL reflash at no charge

I can not post with any certainty that ECU flashes will not be logged and revealed in a subsequent diagnostic at the dealership.

There are conflicting opinions on that VERY important topic.

The law prevents manufacturers from avoiding warranty claims at their discretion

UNLESS they can demonstrate that any action or inaction by the customer is directly attributable to the specific component failure.

xtyper

I have heard to the contrary recently, that it is possible to have multiple ECUs with different tunes working on the same vehicle. In fact I did it myself on my last 2010 model with no problems. Haven't tried on my 2011, but unless MB has tightened things up in their latest programming, I don't see why this still shouldn't be the case.

Maybe you can elaborate on Renntech's official comments on this issue.

cptdaz

+1, the warranty claims can't be rejected on the basis of any modification to the manufactured standards; burden of proof is on the shop/manufacturer.

jvanbrecht

Since the ECU controls all aspects of teh drive train, if you have a problem with the engine or transmission, they can, and will void any warranty work, if your window or radio breaks, that would still be covered under warranty.

As others have said, find a dealer with a relationship with a tuner, and utilize that relationship.

cptdaz

Again it's up to them to provide proof that the changes made to the ECU is directly responsible for the component failure. The investigation for that proof is most likely more expensive than honoring the warranty unless it's something very obvious.

Google "FTC Magnuson-Moss Warranty Act" for more info.

rory breaker

Simple answers:

YES they can see if you have a tune.

YES they can reflash over your tune.

YES if the dealer does reflash over your tune for a new software update or some other reason, you can, under most tuners policies, send the ECU back for a free reflash.

NO the dealer cannot void your entire warranty from an ECU tune. they would have to prove that the failed part was directly due to your modification. If your door lock stops working, they will fix it. If they dont, escalate to MB USA. If you throw a CEL, expect them to not honor your warranty if they know it's tuned.

YES some dealers are modification friendly. Some sell Renntech parts for example and will warranty them. Most however do not.

YES many SA's are mod friendly regardless of their dealerships' position.

YES most people just get tuned and go to the dealer like there is no tune at all when issues pop up, the dealer doesnt think to check for a tune to blame the problem on, they just fix the problem and move on.

NO most people dont buy 2 ECU's and swap back and forth. Certainly an option but not realistic for most.

Strafe1

They can see your tune, but they have to look for it. They won't see it on normal service A or service B scheduled maintenance visits. Best advice though is to develop a good relationship with the service manager and discuss a tune openly with them. Mine was Kleemen tuned and my service manager completely supported me. It helped that he new of Cory (at Kleeman) and the safety of the Kleeman tune.

Pickles

Well, of course you don't have to tell your Dealer that you've had an ECU upgrade, & having had no experience to date with what is/is not done at service time, the dealer may/may not become aware of anything.....but, then, if for any reason, they reflash your ECU, then you would lose your tune would you not.
As far as warranty is concerned, if a serious mechanical issue occured, which could in any way be traced back to the ECU via increased power/torque etc, whether it really was, or was not, caused by the upgrade, I reckon you could have a problem.
Cheers, Pickles.

Nanoflex

Rory...

Thanks for clearing up the doubt about whether or not the dealer can see the reflash.

The onus is on the dealer to demonstrate a customer-installed modification caused the failure of a particular component, in rejecting a warranty claim.

I imagine the dealer could successfully rely upon the argument that the customer's actions resulted in physical stress being applied, outside the normal operating parameters of the engine/drivetrain.

Since the reflash claims to provide only 20 hp more at the flywheel, whether this would constitute unacceptable additional physical stress is open to debate.

Too much uncertainty and too much cash at stake, to take a chance, methinks.

boschk

I tell them when I drop off, do NOT reflash without my permission. I have a tune. They don't care nor have them denied me warranty work. And, if they refuse at any point, they have to prove the damage was specifically caused by the tune, something I'm not worried about in the slightest.

Merc63

Wowzers a lot of crazy talk in this thread.

I have TWO ECU's YES that is possible and IMO the best way to do it! Then you always have your UNTOUCHED STOCK ECU you can pop in and get warranty work done!! I got my second ECU tuned.. How the hell do they know I am actually using the second ECU? All they know is the car is stock and its needs warranty work so fix it.

NO, they can not tell you have a tune!!! My GOOD GOOD friend is a tech and works on my car at the dealer, his tools gave him no indication of a tune being on the car. Perhaps they can send it to Germany or something and do some in depth testing, but he has found no way to see a tune at the local dealer!!

I dunno where you guys take your cars but people HAVE been refused warranty work because of modifications to the car!! One guys engine went KA BOOM and he had an exhaust.. He had to buy a whole new complete stock exhaust, have it installed so the car was stock before they would fix anything. So YES they can deny whatever the hell they want.. Unless you want to waste time taking them to court LOL.

rory breaker

Exactly my thoughts, and why I chose to keep it stock. I do not drive this car hard enough often enough to justify any risk.

BTW - Merc63 what you described is fraud, and if the dealer found out, your buddy would be on the hook for every single penny if not more, unless he could prove that the exhaust had nothing to do with it (which it most certainly didnt, but the quote above describes exactly how they would approach it and he would be screwed). That hassle of secretly swapping stuff out is just not worth it to some of us. Not saying it isnt for you, just speaking on my own feelings.

Nanoflex

Thanx Merc...

See how difficult it is to reach a conclusion when reading unequivocal statements - given in good faith - which directly contradict one another

Today, I specifically asked:

Bob Brady

Senior Product Specialist

Special Projects

RENNtech

(he is a very helpful guy)

whether or not I could keep my stock ECU on the shelf and have them flash a second ECU...

for the very reason YOU mentioned.
___________________________________
Bob replied this could NOT be done - quote:

"I wish it was that easy.

But you can only have one ECU that will work in your car, so we have to
program the one that you currently have."
____________________________________

The other question is the all-important "can the dealership discern if the ECU has been reflashed"...?

My research has revealed contradictory opinions on that yes/no question.

I am also confident that MB will flatly refuse to pick up the tab for warranty claim on a broken, ECU-modified vehicle...

although the customer is welcome to pay a lawyer and take their chances in court.

Thanx again.

Shifter

Well no, it takes about 11 min. to reflash a ME control unit. Granted, this will not be done for no reason. It can be obvious if the unit has been opened up, and modified. But, like others said, if there is no reason to look then who cares--at my dealer we have installed many "tuned" units. My coworker who has a C63 just had his done by Kleeman. I can say, he went from running a best of 12.7 in the 1/4 to 12.3, matching my stock e55 side by side. (although my best run was 12.2 haha. But basically we run side by side now. Woke his car up.

GHAZAN

No dealer will just flash your ECU on basic service unless you are throwing codes and have major malfunctions. And dealer reflashes are done via Germany server, which takes time and effort, neither of which they will waste on your car. Flash away, the only way they will find out is if they open up the ECU and see that it's been opened or you bring it in for a malfunction and they start looking for reasons to deny...

gthal

Maybe in an ideal world... the reality would be different. They would deny warranty and you and the expensive lawyers would then have to fight it. A very reputable tuner for the M3 commented as much on M3Post... i.e. prepare for a real fight (whether you are right or wrong) if there is a warranty issue and the dealer knows you are tuned. Now, knowing you are tuned might be tough....