I bought a gorgeous 2019 C63 S Coupe a couple of days ago from a dealership. Designo graphite grey magno, red and black interior, both carbon fiber packages, and every option ticked other than the digital gauge cluster. The dealership specialized in branded/salvage title vehicles which should have been a red flag, but this was a clean title they acquired at auction and it was exactly the spec I was looking for... so I put the blinders on and marched onward - even past the second red flag: the sales guy mentioned he thought the car had a resonator delete.

After a couple of days of driving it, I've noticed the telltale smell which is even present after light driving. I popped the hood and slipped my phone camera behind the shield that covers the downpipes and lo and behold, it appears there are no primary cats. I'm not certain if the secondary cats should be visible from below without the car on a jack or lift, but sticking my camera down there I don't see them either.

In its previous life, the car was a lease in CA where I know they're pretty serious about emissions, so frankly I'm not even sure how it doesn't have cats. I'm in metro Atlanta, where I'm 1) not subject to emissions testing for another year under the exception for recent-model-year vehicles and 2) fairly sure they just stick an OBD code reader in to check for emissions issues. Does anyone have any experience with emissions here on a catless car that could chime in?

Even if emissions isn't a problem, I would very much like to preserve the warranty. So, I have a few questions:
1. The cats should be pretty obviously visible without removing the heat shield, right? The shield looks pretty easy to remove, but I haven't gotten around to it yet to confirm my suspicion.
2. The car doesn't have any CELs. Does that mean it is certainly tuned? Is it possible to tell without expensive equipment or taking the car to a shop?
3. Has anyone dealt with a situation like this with a dealer? I suspect it's illegal for them to sell me this car, though I'm sure they'll just say they didn't know. Would they be required to do some due diligence to ensure the vehicle is street legal?
4. As intoxicating as the sound is, for environmental reasons I'm not a huge fan of going catless. I've heard some pretty ridiculous numbers for DPs (both part and installation costs) - what's the most cost effective (non-janky) way to get some cats in without seriously sacrificing the sound?

 

2- More than likely it’s tuned.

3- Dealers don’t have to do an emission for 3 years so they wouldn’t have known.

4- You can go to SoloMotorsports and they can weld in some High Flow Cats so it’s not so bad for the environment. Should get rid of most of the smell also. I know they have the exact cats needed in stock for C63.

 

This. And yeah, the cats would be obvious.

 

Good to know.

elitex: Any idea how much Solo would charge for that? My biggest concern is warranty - not too keen on owning something with an AMG badge on it with no drivetrain warranty. Any experience with the dealers around here? I'm fairly sure the car had an inspection done by MB Marietta (it shows up on the carfax; I'm trying to get a hold of someone there who can get me a copy of it + any other service history details), just hoping that they didn't already report anything to kill off the warranty.

 

If it’s tuned then drivetrain warranty is already toast. Getting Cats done would be about $1600 with labor as the cats alone are roughly $900.

I would definitely get a copy of the inspection report. These cars are fairly reliable so I wouldn’t sweat it too much. If there’s an issue that dealer wouldn’t cover then you can always have Solo fix it for fraction of the cost.

 

Well, hopefully it isn’t tuned then. Any way to tell without taking it somewhere? I’ve read a couple of places that there _is_ a way to avoid the CEL without a tune but it seems spotty.

Solo is great, but with a warranty if something is broken it’s free from the dealership — whatever they’ll charge is definitely not a fraction of $Free

 

Obviously. My point was that if your warranty is toast.

 

You could probably run it on a dyno and see what kind of power it is making to the tires. That'll tell you if it is stock or tuned.

 

if it’s tuned your warranty is out the window. Even after flashing back experiences techs will find out it was tuned. JMHO

 

Not necessarily. They'd have to prove that the tune is what caused the issue.

There are also service advisors out there that will look the other way when it comes to a tuned car.

 

My SA stated that MB likely won’t dig into Ecu unless major Engine or Transmission issues. I don’t think MB is doing it like Audi where they automatically flag and void warranty.

 

all depends on your MB shop. But if they find out they flag it and warranty is void no matter if the issue is caused by it. Just the way it is. Usually, if they have no reason they will not dig in to find out but only if something breaks and they start to deep dive into diagnostics.

 

i think the dealer must have checked my ECU because my SA called and said he just noticed that the sec cats were gutted and asked me if I ever tuned the car. Didnt have a tune otherwise im sure they would have blamed the extra torque and would refuse to replace the rear diff.

 

well, good luck. If the cats are gone and no CEL you got a tune for sure.

 

How many miles on the car? Sounds like the car is tuned.

 

20k miles. I've seen a few on here talking about having no CEL with catless DPs, but it sounds like I won't be able to tell for sure until I take it somewhere.

 

Yea I have a W204 with catless headers and no cel, my tuner turned it off so I think you might be in the same situation. I think your best bet right now should be to try talking to the dealer you bought it from to see if they can make it right, maybe get them to buy the cats, and to pay for the install. There are rare cases where people with tunes are still able to get work done on their cars. I know someone that got warranty work done with downpipes and a tune in another car (Audi and BMW). So best of luck honestly, these cars are pretty reliable but if something does go wrong (hopefully nothing will during your ownership) it will not be cheap to get it done at the dealer.

 

don't think so - catless DP w/o a tune and you get the CEL after a few miles.

 

If it has catless DP’s and you don’t see a CEL, it’s almost definitely tuned, and your warranty is almost definitely voided. Who did your PPI, Helen Keller?

 

If your car is subject to an emissions inspection that is run through the OBD port, it will more than likely fail the test even if there is no CEL. The test checks the OBD Monitors to see if they are "Ready", and in order for your car to pass all but 1 or 2 of them need to be "Ready" (exactly how many depends on your specifc state/county). The way a tune prevents the CEL from coming on when you have downpipes is by turning off several of these sensors within the exhaust system, but this prevents several of the OBD Monitors from setting as Ready. The emissions test will easily see this and fail your car.

 

Update re question 3: I contacted a dealership that inspected the vehicle before the dealership listed it for sale and got a copy of their report. It clearly states "rear cats have been deleted" as part of their inspection for something unrelated (blind spot monitoring failure). So the dealership absolutely knew that this vehicle had a tampered emissions system. Does that change the calculus as to whether the dealer should be responsible for the repair? Obviously used car sales always have "as is, no warranty, buyer responsible for all repairs" etc plastered all over them, but my understanding is that in cases of fraud (i'm fairly sure this would be considered fraud) such conditions aren't enforceable. Any thoughts?

 

I think you have a very good case - as it technically is not legal to drive on the streets. So. they sold you something you are technically not allowed to use legally...and the evidence was there for them to know about it, i.e they can not hide they did not know. Did they put the tags on for you? Than they basically broke the law. I am sure they will fix it so that you dont make a big deal out of it.

 

Wait, is it just the rear cats that have been deleted? Have you checked to see if you actually have the aftermarket downpipes?

 

yeah, if just the rear pots that would explain why o CEL w/o a tune....

 

I haven’t pulled the heat shield off the turbos to get a better look yet, but I’m looking through the openings in the shield and I see what appears to be just downpipes — no cats. I can’t find a picture of this part of the engine on a stock car, but looking at the stock DPs in diagrams it looks like the bulge from the cats should take up almost all of the space under that heat shield, and they don’t. I can try to get a decent picture of that at some point, but just drove so the car is hot right now . I can get under the car enough to be sure the rears are deleted.

I suspect the dealership didn’t look at the primaries, which is why it isn’t noted. The car was at the dealership for a blind spot monitoring issue, and the service note reads as though they put it on a lift to get to that module and happened to notice the rear cat delete.