I can’t find a definitive answer whether we can buy a spare ECU and tune it, then swap the original in when going into service. I see the W204 folks do it, but no examples on our platform from what I can find.

Can we do it? How about the mileage? Isn't it stored in the ECU and swapping ECU’s would cause a mileage discrepancy? Would this be a 100% safe way of avoiding detection?

I really want a tune, but not at the risk of losing the warranty, considering i still have 3 years of it.

1. Yes we can do it
2. Nothing is 100% safe for warranty
3. If you have doubts don't do it
4. AMS cloned my ecu
5. Nothing is 100% safe
6. I have 3 years of ELw warranty left and have no worries

With the new OBD tuners that allow you to switch back forth between tunes, you shouldn’t need a different ecu, should you?

its one extra level of espionage for thwarting the dealer ... that's all

any time the stock software file on your original ECU is modified the file checksums are altered which MB Germany can detect (dealers maybe not able to)

So take the stock ECU, flash a tune, then revert it back to stock the file the file checksums are altered every time. Checksums are how all software files compare and detect data errors in a software file which my understanding is MB Germany (not dealer level) can detect and could explore in a warranty claim if they suspect a tuned ECU causes the engine issues

not sure what they detect with swapping.dual ECU when the original is not altered.....

I imagine there is a log in the ecu of when it was powered down and on; meaning when is lost standby power (i.e. I'm switching it out for tuned ecu)

Perhaps there is a time stamp when a voltage change is detected and just enough energy is stored in capacitors to write one last time stamp


im reaching here ...

Hey Peter,

First of all, thank you for the wealth of information!

Much like yourself, I am not much of a gambler when it comes to the warranty on a $100k car, so I don’t want to dive into this unless it’s a pretty safe bet. Have you swapped your stock ECU back in for dealer service? No issue with mileage discrepancy? Or something else i am overlooking? I wonder if the dealer can tell the stock ECU’s been out of the car, meaning the car ran on a different ECU.

you and I are cut from the same cloth

yes, just had the 30k service done, stock ecu went in and no one said anything to me. I had $2000 job on the engine ... tensioners replaced ... no issues with warranty

i paid $350.00 for a used ecu from a donor 2015 gl550 on eBay

I am very much into modded AMGs and most definitely not to try to scare away people of tuning the ECU, but spoke in length to the service director of my dealer whom I have know for over 6 years. Here is what I know, Mercedes ( MBusa ) can remotely get data from your Mercedes and that is not surprising. But how this answer the question if using 2 ECUs can avoid getting the warranty voided ( Flagged or status 8 means dealer needs prior MBusa approval before any warranty can be done. Status 9 means warranty is voided and no warranty work, don’t ask, don’t touch ), the answer is. Once your car has α major engine or transmission break down, Mercedes sends α master tech to that dealer and the first thing that tech does is take out the wheel Axel rod and takes a long look to see if the axel rod is bent. Mercedes design the rod to withhold the stock power ( tq ) and once the hp/tq is increase because of the tune, the rod gets bend and twisted inside the axel housing. Once they see the rod is bent, you are on your own.

FYI, the said dealer has α 2018 C63s with 6k miles on the clock and it has α ECU tune there now and that is exactly what Mercedes and the Mercedes master tech did to verify if the car was modded and guess what, the owner now needs to foot the bill for the repair.

I am guessing that is why tuners don’t want to mess with the TCU.

Again not trying the scare anyone, but that is how α very reliable dealer/service head with 25 plus years experience explained it to me.

What was one of the first thing I learned from this forum when I got my first AMG was. One, don’t own one without warranty and the second is you got to pay if you want to play. Not trying to be sarcastic, but I have seen it happened to a few owners to hold water.

AMS

You PAY TO PLAY: I get that if I blow my engine I either lose the value of the car or have to pay for a huge repair.

anyone that tells you otherwise is uninformed or very much in denial.

totally agreed

It made sense to me. I mean if Mercedes is going to drop ship an entire engine which is about 20k retail and then another 5k on shipping, I would want to know why the engine is dead too and what better way to check is the axle rod.

But again I’m sure there are allot of owners who does have something go wrong with their engine and don’t have a tune.

Just a draw of the hand I guess?

Don’t mean to be a stick in the mud, but this axle rod thing sounds a little farfetched. Are there no symptoms of this axle being bent? Like a noise or vibration? And if so, why couldn’t one replace it? Not to mention, a stock car with slicks/DR’s will be a lot more likely to bend this axle rod (stress the drivetrain), rather than a higher HP car on street tires aka crap traction.

My worry is if the ECU keeps mileage. Or some way for them to know the car was ran with a different ECU. If there is not, the 2nd ECU might be the loophole.

Do we have or know of anyone here who’s had an issue with a 2nd ECU and warranty?