Dual ECUs?
 

Already posted in C218 forum as I own a cls550 lol, but that forum is a bit dead sometimes so I'm posting this here too, since the W212 and c218 share basically everything but the swoopy roofline!

Hey guys, so just to make this as non boring and straight forward as I can, would using two ECUs, one tuned and one stock prevent MB from seeing I had a tune on the car?

I ask this not to seem like a cheating charley, and defraud MB for my own actions, but I also don't want to be held holding the bag for something that had nothing to due with a tune. I do know if MB knows I have a tune, they'll 99.9 point to that, even though it had nothing to do with a power train failure in question.

From the very very little I know about ECUs, I highly doubt this is possible. And even if it were I doubt even more that you could hide it from MB.

I'd suggest looking at this solution. I would call RENNtech to see how if the car would be flagged when reverted back to stock, but if it works this would be far cheaper and easier.

https://www.renntechmercedes.com/index.php/products/hht

You can definitely get a second ECU and tune it. Lots of owners do it on the AMG side.

Of course you can get a second one. But it would have to be from the dealer and it will have to be programmed and coded online. Which means, Daimler will know a second one exists. What year is your car?

I was told I can get a used from like eBay and have that one reprogrammed? And my car is a 2014!

Would the dual ecu route keep me somewhat protected from false Blame?

Given the responses so far, it appears that Mercedes will know of a second ECU, regardless from where you get it... They are the only people who can program it. Further, not sure why you are concerned with MB's knowledge of a second ECU, because your 2014, 4-year factory warranty is expired anyway. Not at all convinced that any supplemental warranty will cover this part, either.

I suspect that if you present a second ECU -- not purchased from Mercedes -- to the dealer for programming, you will be required to show proof that you properly (legally) own it. It belongs in another car, and unless you have a salvage certificate or some other paperwork from the eBay seller that satsifies the dealer, I doubt the dealer will even speak with you about it.

Someone can correct me, but I don't think switching between cloned ECUs is a simple plug-n-play operation in any event.

I’m sure he must be on a CPO extension or extended warranty to be concerned. I still have 2 years left on my CPO extension for my 2014.

At some point you have to roll the dice to play in the Horsepower game.

Yes I have 2 more years of extended warranty, and by the time the warranty ends I'm more than likely gonna trade it in for something else. So I'm Just going back and forth right now on whether I want to tune the car, or not :/

A couple of the tuners on here have told me that I can send my stock and and used ecu In, and they can program the used one as a tuned one, and my stock stays stock.

My second paragraph still stands. You will need to prove the second unit is not from a chop shop. So make sure the eBay seller can prove that to you with paperwork you can then show the MB dealer.

Buy the second ECU from MB, instead, and you avoid this hassle... the provenance of that unit will be known to MB.

Here is the thing...... some where mid 2014 Mercedes went from the DAS3 system to the DAS4 system. If you have a DAS4, I highly doubt tuners can program a second hand ECU. You could do a reman unit but it has to come from the dealer and it will be ordered using your vehicle's info. If you have a DAS3, it can be done with out even programming online. I have the equipment to do ECM'S, TCU'S, EIS, KEYS, ESL and ISM's but I can only do DAS3. No one can work with DAS4 right now.

Kind of a catch 22 with buying a ECU from MB lol.

My car was probably built sometime in 2013 if that would make any difference?

PM the VIN number and I will tell you if you have a DAS4 or DAS3.