2020 CPO GLC63 - Performance and Engine Issues - Advice and Opinions appreciatedOn 10/3/22 I bought a CPO Pre-Owned GLC63 AMG with 12K miles.
It is still under the Factory Warranty until 12/2023, then the CPO kicks in until 12/2024.
On 10/15th I was ordering New All-season radials for it and when I checked the passenger front wheel I noticed that two of the lug nuts were stripped and only in there hand tight.
One other lug on that wheel was so swollen I could not get it off. There were one or two other swollen lugs on other wheels I could not get off.
It took my local garage almost an hour to get that wheel off, making me question if the car actually went through the stringent CPO process, there is no way they could have inspected that wheel's brakes, rotors, etc...
The dealership actually reimbursed me for the 20 one piece lugs I had to order to install my new tires on 10/19th.

Now to the engine/performance....
On 10/27th my Engine light (cel) came on.
I called the dealer and the service advisor told me as long as the light is not flashing it is safe to drive and give it a few drive cycles to see if the light goes off.
On 10/29 the cel was still on and my local garage scanned the codes and got:
P152B00 - Current - leakage in inlet air system - cylinder bank 1
P227900 - Current - leakage in inlet air system
P002177 - Stored - inlet camshaft (cylinder bank 2) differs from specified value, camshaft position cannot be achieved
P012800 - Stored - engine coolant temperature is below the coolant set temperature.

I called the dealer again, they said safe to drive and they set appt for 11/18th.
The CEL went off a few days later.

On 11/12 I hooked up my dragy and did a couple of 0-60s:
4.23 and 4.15 - (3.85-4.0 with rollout)
On 11/14 the cel came back on.
11/18th took the car to dealer and they got code p012800
11/22 - they updated software and cel went off.
11/23 - picked car up and on way home from dealer CEL came back on.​​ I hooked up dragy to try a 0-60 with cel on and got a 4.89. Called dealer and set appt for 12/12.
12/1 - cel went off
12/2 - tried a 0-60 and got a 4.50 (4.24 with rollout), definitely down on hp.

Looking back at my carfax on 6/22/2021 - went to dealer and "body electrical system checked"

Keep in mind, I am not using the Original Dealer for service, they are too far away, I am using my local dealership. For my next service appt there I am using a service manager my son knows personally.

Any advice, experience or opinions as to what is wrong with this car would be appreciated.
I am wondering if the car had been tuned originally or modified and not restored back to stock correctly.
I have no problems with a tuned car, but they would not be able to CPO that car.

Wednesday 12/7th the CEL is back on.
Car has 14,209 miles.
Dealer picking car up 12/13th.

Today 12/15/2022 the Service Department reached out to me.
Mercedes had a bulletin about this problem and said to check the Thermostat Operation which was found to be OK.
If the Thermostat was OK the bulletin said to Bleed the coolant system which they did.
They said this will solve the problem.

I am skeptical.
I truly believe there is some sort of leak in the air intake system, but I will get the car back tomorrow and hopefully all is OK.

Drove to work with it today, 12 miles from home at 14297 miles the CEL came back on.
Dealer is picking the car up again tonight when they drop my wife's car back off.

I called the dealership I bought it from.
They said the car was checked out according to CPO and they stood by it.
They offered to take the car to their shop 60 miles away and check it out if my local dealership cannot get it right.

I am really frustrated, I know it is a first world problem, but it still is annoying,
I paid good money for the car and it is in the shop more than I have it.

The original dealership says they will make things right, but they also said they understand if I call corporate.

Update:

My local dealer decided not to pick up the car.
They said they can't fix it and sent me a Service Bulletin from Mercedes which I will attach claiming the car is safe to drive and there are no performance issues.
However, they did not replace the Thermostat, they only bled the coolant system.
Also, the performance of the vehicle according to my dragy shows it is off on power. 4.5 (4.3 rollout) 0-60 is way off.
My previous best was a 4.1 and 4.2 before the CEL issue started, about a 3.9-4.0 with rollout which is more in line with the 3.8 Mercedes claims for the 469hp engine.

I spoke to two people (used car manager and my salesman) at the dealership I bought it from and they said they will make it right.
They are 60 miles away, so I told them if they are willing to pick it up and bring it back I would give them a shot at it.

I still think they are missing another problem and only dealing with the coolant system. They are not even looking at the other codes I provided.
I do notice the CEL seems to come on when I put in my Individual mode or Sport Plus, makes me wonder if there is a tune on this car maybe based on mods that may previously been on the car?

 

From the other thread on the site, the notion of whether a few tenths on 0-60 really matters came up. Does it?

The car is under manufacturer warranty. Work with the dealer to find satisfaction. If no joy with the current dealer, go to a different dealer.

 

The dealer I purchased it from is picking the car up Wednesday morning and gibing me a loaner.
My Porsche is going in to AIM performance for a tune and other stuff so I need a car to drive.

As for the 0-60 times, yes it matters in the fact that I know it is because something is wrong with the car.
If I get it back, the car gets a clean bill of health from Mercedes, and the CEL stays off, at that point if the car is still slow 0-60 I will deal with it, but...

Since the car already ran a 4.1 and now cannot do better than 4.5, it most likely indicates a problem.
The dealer who sold me the car seems to agree and says let's get the car a clean bill of health and go from there.

 

In regards to your problems I can shed some light. For starters I own a 21 C63S saloon with 21k mikes on the clock. At around 18k on a road trip to Vegas my engine light came on and I had it scanned at the local shop. Mine through a P0128 just like you. local dealer performed everything in the service bulletin and bled the system the tech stated that they bled it for “4 hours under vacuum instead of 30 min” like the bulletin from AMG said. Long story short the thermostat assembly was replaced under warranty and it’s not a cheap easy job. Calls for about 8-9 hours of labor the front Intercoolers need to come off as well as the radiator package assembly. The thermostat itself was over $800. The job alone is easily over $2500 so make sure you get this taken care off while still under warranty! And as far a the other codes the cam magnets are a common fault and can cause breathability issues. Those can be replaced as well while the thermostat repair is in progress while the entire front end is apart hope this information helps!

 

I'm sorry I stopped reading when you said 60 miles was too far for you to bring the car to get it fixed correctly. Push for the repairs in this ^ post and go to the dealer you bought it from ffs.

 

I was told the main problem with this code on the M177/M178 engines is the 3 disk thermostat itself failing mechanically. Theirs 3 different positions it’s able to achieve based on coolant temp, ignition timing and the control signal from the DME to the electronic heater built inside of it. If it fails to meet a certain position and the coolant temp isn’t achieved within a pre-determined timed threshold, the code will set and the vehicle will go into soft limp mode limiting power. Hence why your light comes on and off. Your thermostat is getting jammed mechanically and there is no “easy” fix except replacing the thermostat assembly in its entirety. If the dealer is giving you the run a round take it to a reputable German specialist shop, pay for a diagnostic fee (make sure they know how to perform correct and accurate electrical troubleshooting and diagnostics) and take that diagnostic fee and report to the dealer and make them replace the damn thermostat. Tired of these loser dealers and techs not knowing how to fix cars!

 

Thanks so much!!!!
Did your car run better afterwards?

The local dealer was supposed to do the thermostat and instead they said they checked it and it was not faulty, I think they just did not want to do the tedious job.
I am sure the dealer I bought it from will do this job, heck MB corporate is paying for it under warranty.

I believe between bleeding the coolant correctly, changing the Thermostat and possibly the fixing cam magnet issue the car should run as it should.
There has to be a reason the car through those intake and cam position codes.

The car is definitely down on power.

Thanks again for the help.

 

I agree, the Thermostat is probably the issue and although the car drives fine during normal driving, it is definitely not making full power, and probably in limp mode.
It definitely does not seem to have the snap it should have.

 

There are many reputable MB dealers near me, I should not have to drive 60 miles for a warranty issue.
However, the dealer 60 miles away is picking it up Wednesday and is committed to getting it right.

 

Yes, it ran perfectly normal after. I have been trouble free with no thermostat codes ever since. There is no other fix other than replacing the faulty thermostat, unfortunately only certain models had defective units assembled at the plant. my vehicle was one of the affected engines that they had experienced. My local dealer opened up a case with the AMG engineers and they told them to replace the thermostat after having the vehicle a week. they performed "Timed" road tests while recording and analyzing data parameters. I really hope your dealer gets it right and fixes you up. its ashame to see such a beautiful vehicle and powertrain not ripping the streets like these engines should. Best of luck.

 

Good to hear.
My car is definitely not ripping up the streets, I love driving the car, but it is not performing as it should.

 

Big thanks to Shlick96

The service department called me today and they confirmed the car is not running right.

They pulled all the codes and are:

1 - Replacing the thermostat
2 - There is a boost pressure leak and they are going to fix that also.

 

Glad they sorted you out. I have to drive 150km to get mine serviced and am happy to do so. Luckily...my 2019 has been bulletproof thus far. Let us know how she runs when fixed.

 

I am glad to hear this. Keep us posted afterwards. You should be running back to normal after the repair.

 

I will keep everyone posted. How many miles are on your 2019?

Thanks again!

They have not mentioned doing the cam magnets, hope that is something they check out.
I will ask when they call me with an update.

 

I have about 12k miles now. Had 4k when I bought it back in late August. I drive the crap out of it!

 

Mine had 12K when I bought it and the problems started soon after, you should be good.

 

your telling me! I have a 21 with 21k already on it. It’s hard not to drive this beast. Such a great aggressive powertrain.

 

Glad I could help someone out with the same problem! I’m curious to see where they find the boost leak? Hopefully it’s just a simple vacuum line and not an intercooler or something crazy.

 

Today is day 6 since I last heard from them on 12/22.
Hopefully I hear something today or tomorrow, but I want the car back right, so I am willing to wait a bit.
My Porsche is going in for a Tune, coil packs, plugs, and an oil change next Tuesday 1/3, it would be nice to have it back by then, but I am not counting on it.
It is so cold and lots of road salt on the roads, so using their Mercedes loaner car is not a problem.

The last thing I want is to get the car back and within a week the CEL comes back on.

 

The car is done and being brought back tomorrow....

Shlick96, you are the man!

1- they replaced the cam magnets while they were doing the work.
2 - they replaced the thermostat
3 - they found boost leaks at the crank case and other leaks while they were in there, so they replaced all the lines.

The tech told the sales manager I will be very pleased and that is is an animal now.
They said it was not making much boost before and it was performing terribly when they got it.

Will update when I get to drive it.

 

Great news bro.

 

After I get it back, drive it to and from work a few times with no CEL and do a couple of Dragy runs I will feel a lot better.

 

I got it back this morning, it is rainy, but the car feels spunky.
Also, for the 1st time my temperature gauge is 208.

Here is the work that was done, pretty extensive.

 

That would have cost a pretty penny without warranty.