I’m in the process of selling my 2016 C63S sedan to move into a 2017 C63S coupe. To make a long story short, I thought the sedan would work for me but it didn’t so I’m getting the car I want for a good deal. I currently have two offers for my sedan. One is with Carmax with a short-term offer and the other is with an individual who responded to my offer.

My problem: I have an ECU tune from one of the reputable tuners (I won’t name who but they have been listed on this forum) and love the power delivered by the car. My dilemma is (1) whether or not I need to reveal I have a tune to the buyer, (2) I can legally transfer the tune to the buyer, or (3) if I have to return the car to stock, how do I do that?

I get this feeling #3 is really my only option so I’m wondering if is there an easy way to return an ECU to stock without pulling it again and sending it off for flash. It was a pain in the butt to get it done the first time and I was without my car for about 7 days due to a mix up with returning the ECU. I’m hoping there is some other way to return it to stock. Also, has anyone ever gone to a dealer to flash the ECU back to stock without getting the evil eye for an after market tune? I’m willing to go this route but really don’t want to because I plan to buy the coupe from them and have the same ECU tune added at a later date.

I’m hoping there is an easy (and cheap) answer and solution here. The buyer is really eager to get this car and I really can’t wait to get into the new coupe. Thanks in advance guys for any feedback or advice.

 

I don't think you have any legal obligation to tell the buyer but maybe a "moral" one. If I bought a c63s and something went wrong and I took it to the dealer, only to have my warranty voided over a tune I didn't even know existed, that would be pretty ****ty. You can maybe ask him or her what they want, though there is a change they will walk if they think the car was abused.

 

It's illegal to list it as "stock" in an AD or telling the buyer it is stock when asked. It wouldn't take the buyer long to run the car's vin # with the reputable tuners.

PS - It's pretty crappy not to disclose that information to a potential buyer but at the same time that is why you get a certified used one to avoid crap like this.

 

Certainly don't hide it. Not sure that is your intention. Why not just trade it in to the dealer as part of your coupe deal and be up front with them. Your financial lost might be less than shipping your ECU off for a new flash. This is one of the reasons I went with the piggyback, which ultimately failed and is gone now. Without OBDII access, you really have no other way to manage the ECU tune without access to the ECU. By the way, can the tuner even flash your car back to stock? I recommend calling them for advice.

 

I agree and don't plan to do anything illegal, immoral, or harmful in the transfer of this car. This is not something I've done before so I'm hoping someone can share an experience or expertise in the area. It's likely I'll have to remove the tune but I was hoping to learn from someone else's experience with this situation. Unfortunately, I'm up against the clock so I thought a useful "shortcut" might exist to reset the car without a week's wait.

 

This might be your best offer. I can tell you that I plan to get my ECU tuned in the next couple of weeks and have been quoted ~$400 for labor to remove the ECU. If you have the luxury of waiting for the car while it is reflashed, just pay this fee. Otherwise, don't waste your time parking your car on a lift for a week while waiting for the ECU to be returned. Just give the dealer your car, take your loss, and enjoy your new ride.

 

I am pretty sure that when the dealer does a software update it resets the ECU and wipes out the tune. They have the ability to do this through OBD and do not have to drop the tranny. Even if you have to slip the Foreman $100 to do it, let MB reset the software or look for a bulletin on the car and let them re-flash it.

Problem solved.

 

^^^This, or...
I don't see what the problem is with selling the car to CarMax as-is. They do their own diagnostics prior to purchasing.

If they like it, they can make you an offer on it and buy it. No one is forcing them to do anything.

When I took my car there to get an estimate, they ran a Carfax on it... Came up clean. I knew it had been in an accident, and fixed though insurance, should have shown up. But it didn't.

I didn't feel any obligation, moral or otherwise, to disclose anything.

Just my 2 cents.
​​​​​

 

I think you're overthinking this. If selling or trading the car into a dealer you don't have to tell them anything. As a matter of fact it's better to just keep quiet unless the work you've done on the car is to your advantage. I think if someone is interested in purchasing a C63 a tune on the car that's been done by a reputable tuner is a good thing. That's money the buyer saves and no hassle of pulling the Ecu out and sending it a tuner blah blah. However i definitely would just disclose it with an individual purchasing the car and let them know it can be reverted to stock and be honest about whether or not the car's been pushed to its limits.

 

What many of you are failing to see is that if the car has a mechanical problem that requires the dealer or insurance company to check the diagnostics/ecu and it shows up as altered, then the cars warranty is not honored.

If this poor guy drives right into the back of a truck and totals his car, they "could" check his ecu and refuse to honor the insurance.

If he blows his tranny and the dealership sees the tune, MB will not repair it under warranty.

Since there is no way for a buyer to know if it was tuned, by not disclosing it you are opening yourself up to a lawsuit, forget the ethics behind it.

If the buyer is a young guy then maybe ask him and see if he wants to keep it tuned. Get it in writing that he understands the car was tuned and takes responsibility for it. If its an older guy, you might just want to flash it back.

 

Lol just ask the guy if he wants the tune or not. Very simple.

Def do not sell it to him without disclosing for said reasons already stated above.

 

Really?!? Insurance won't cover a car with a tune. Never heard that one.

Should someone with an aftermarket exhaust worry?

Aftermarket wheels?

As far as the warranty goes... I would think the "ingorance is bliss" argument would work like a charm for a buyer that didn't know he purchased the car with a tune. Hell, even if he did know, lol.

Guaranteed, if I was the​ "ignorant" buyer and ran into an issue, mbz would be covering me.

 

OP, its been said so don't overthink this decision. I agree that Carmax or dealer trade might be the way to go. Morally, you can do whatever your conscience can handle but I don't recommend taking chances with potential legal issues. If you can get "AS-IS" added to your carmax offer, go get your coupe.

 

In the UK any modification to a car which hasn't been mentioned to the insurance company might void the insurance, yes - wheels, exhausts and even wraps. Recently (last couple of years) I've been asked to state all manufacturer options fitted to the car when insuring it. On some cars the list is just ridiculous!

When I sold my C63 a couple of weeks back the dealer asked me to sign a form that there were no tunes or custom mods on the car. The car was stock.

I have heard, indirectly, that a guy who bought a low mileage RS6 had to take it into a dealer for an engine fault the car turned out to have a tune and was TD1'd (warranty void). The last I heard was that he had to pay to repair the fault despite having no knowledge of the tune.

The UK does not have the Magnuson–Moss warranty act which protects you guys pretty well. It probably makes selling cars with tunes far less important in the US.

 

Interesting. I had no idea. Sounds like a real sh** show in the UK.

Nevertheless, I believe the OP is in the states... So much of the advice in this thread likely doesn't apply.

 

Thanks everyone for the timely and helpful feedback.

UPDATE: Shortly after I started this thread I called the individual buyer to disclose the tune. While he plans to get his own tune, he is a bit nervous about my tune and the company I used to modify the ECU. I totally get it and would have the same concerns. He agreed that I should have it removed (because of recent troubles with the tuning company) but his new concern (and mine) is that the dealer will flag the VIN and he'll have to deal with the fallout. We agreed that if I can get the ECU flashed to stock this week, we have a deal. My next move is to reach out to my CA to find out if a reflash is something they can do without reported problems, how much it might cost, and whether or not it affects the warranty. I suspect they can do anything for the right price but the warranty is the true concern. If this doesn't work, back to Carmax for a second appraisal and offer. Thanks again.

 

Not to kill your newfound plans, but you should check out this thread before going to the dealer. If this turns into a real PIA for you, you might consider buying a new ECU at wholesale prices to wipe clean this tuning issue. Just saying...

Those with Tunes Be Careful...My Story with MB: https://mbworld.org/forums/w212-amg/...-story-mb.html