Okay you and your Xentry guy made great fundamental diagnostic work - respekt.
Thats the way it goes if problems on such cars.

Use Xentry & use your bain - thats the way it goes.
And have some specific knowledge of technic of the car. Combinte all = error detected. ( in theory but mostly in praxis too).


I know there are two indipendent cooling circuits.

a) transmission, intercooler and ??? / no coolant level sensor in the reservoir

b) engine / coolant level sensor in the reservoir


a.) has only a electric cooler pump
sometiomes i heard this pump can go faulty ( and transmission temp rise up)
but i dont know if error light in combi lights up or only error code in modul.

b.) cooler pump is only by beltdrive ? or is there a electric pump extra ?


The error code camshaft sensor you can check this sensor , check the plug from the sensor - oily ?
or maybe sensor is faulty inside . Replace.


E- Motors flaps exhaust.
The error code means short shot ?
I dont think its the wire somewere from modul to e-motor flaps i think this meams the e-motor ( acuator) itself.

Is in the fault codes a location noticed which acuator ?

With U78 you have 3 acuator flaps, one in the middle , two on end of exhaust. i would guess the middle flap do not realy matters ( i think its only for sound). the others do sound and responsible for exaust pressure.

have all this flaps a responsible (exhaust) modul ?
i would guess.
i think the middle flap makes engine control unit module .
the two ohers have a seperate module (control unit)

Only a guess!


I would unscrew the two acuators on end of exhaust put some +/- on them and look what happens. plug has three-pole + - and ?.


Then check flaps mechanismen if he goes easy or he jam‘s.

The solve problem.

After this clear error codes makes a test drive & check error codes again.

Then tell us more.

@perkpal you have a few things going on for sure.

1. The exhaust flaps "short to ground" doesn't automatically mean a wire is touching metal. It could be internal in the motor. Malfunctioning exhaust flaps have also been known to cause the boost condition you described. So I'd start there.
   • First I'd run the engine and look down the exhaust pipe with a flashlight while someone else pushed the button in the car and see if they move.
   • If they don't move, I'd take off the actuator motors and rotate the flaps inside the exhaust pipe by hand to see if they move freely. If the flaps themselves are stuck you might be able to free them with some spray lubricant, or else an exhaust shop will have to cut them out and weld in new ones. If the flaps move freely by hand then you probably need new actuator motors.
2. While you're under the car you should check the valve and actuator motor in the center H-pipe section too.
3. The cam position sensor fault may just be oil in the wiring harness, or a faulty sensor.
   • Pull the electrical plugs off and clean them with electrical connection cleaner.
   • If that doesn't clear the code then replace the cam position sensor.
4. The throttle position recalibration is the last thing I'd work on once you get everything else taken care of. The throttle bodies are very hard to get to, so it's difficult to clean them. But a recalibration just ensures that they are opening in correlation to the right amount of throttle input. An old tuner trick to fool a customer that the car is more powerful was to change the ramp rate / slope of the throttle input. In other words, program the computer that 10% throttle input should move the actual throttle body blade 20%. This would cause the customer to think that "my car is way more powerful now because I barely step on the gas and it takes off" when in reality it's just programming that makes 10% input on the gas pedal actually equal 20% at the throttle blade. The reason I mention any of this is that your correlation values may be off and when you are at wide open throttle on the gas pedal the value at the throttle body might be 95% so as the engine climbs in RPM it thinks you've let off the gas essentially due to the mis-correlation.

Thanks guys, this is really helpful! I was afraid for short moment that I would be taken to the cleaners (or at least attempted to). Will definitely check out the cam sensor plug/sensor itself (edges of the airbox look a bit shiny, not leaky with oil, but sliiightly oily). And the exhaust actuators. Hopefully this will all be over soon. MB dealer quoted me 700 eur for 2x exhaust flap actuators. My local AMG specialist quoted me 750 eur 2x exhaust flap actuator with labour included, seems fair so I will go with that. Do the left and rear have the same part nr? MB dealer told me there is a new updated part nr, even for my older pre facelift car (205.287), do you guys know what this part number is?

Local AMG specialist will also clear the codes as I don't have Xentry. Chain stretch and variable timing system failure is not happening already at 80k km on these m177 engines right? (car has been very well looked after, full service records, a service pr year minimum no matter if it didn't drive that much, and never punished or tuned, 3 owners total, I got it at 44k km only)

Best regards,

I dont know for sure - but i would guess le & ri are the same.

partnumbers old and actual ask MB Parts guy.
tell us too.

@perkpal

Are you still alive ?

Something to tell us ?

Hi guys, work got a strong hold on me these few past weeks, that’s life. Update: unfortunately no major update, tomorrow I have agreed to take the car to my local AMG specialist, originally we agreed to just directly get the exhaust actuators replaced. But now he says he wants to make 100% sure it’s those that need replacing before he orders the parts (can get them OEM new faster than me I think). I think it makes sense, but he said he was unsure how long it would take to check things. In my mind there isn’t really much else to check other than the short wiring to the actuators and maybe the connectors. I will ask him for short inspection + Xentry print out and clearing of codes. What do you guys think?

Best regards,

Sounds good.

He should check all 3 flaps ( not forget the flap in the middle).

Okay thanks jack, good to check it to be sure. However, there is absolutely no stored or active error from the flap in the middle. But still smart to check while it's on the lift

Best regards,

Hi lads, sorry again for the late updates — work got in the way as I mentioned before. These last two weeks felt like two months!

I just had the car checked at my local AMG specialist, and it turned out to be two fuses (OMG what a *******g relief) related to the rear exhaust flaps that had put the car into a soft limp mode. Everything is running fine now!

That said, the actuators and flaps themselves can still fail, so I’ll keep an eye on them.

Regarding the intercooler: the faults only appeared after the low-temperature circuit wasn’t properly refilled. My local AMG specialist had cleared all codes prior to that incident (so I don’t think they had a fair chance to catch this), and the errors haven’t returned since they were cleared by my friendly Xentry guy / tuner.

The camshaft error was likely triggered during the soft limp mode when I have tried to make many kickdowns to recreate the boost drop (maybe this is wishful thinking on my part, please pushback on this if you know more) — I’ll keep an eye on that as well. It might also be a good idea to check that the camshaft sensors aren’t contaminated with oil (which can happen). Now how to do this without messing up.

The latest Xentry report shows no current faults.

Thanks again for all your support guys, turns out I wasted a lot of money and labour for complete vacuum hose set for turbos (preventative maintenance haha, I asked for this myself instead of letting a mechanic look thoroughly through the symptoms) and almost wasted money on two new actuators. It was two fuses all along (I’m a bit embarrassed I didn’t figure this out, they sit in the passenger footwell, I knew about the 3 fuse boxes, but I was blinded by imaginary potential engine problems). The first Xentry report I got myself was very good starting guide. Let this be a cautionary tale haha!

Best regards,

We are happy with you.

2 fuses for 50 cent make such a big problem - holy jesus.

Some things are so simpel an fundamental.


I ask me is there a fuse map for C63s ?

Allways doubble check the fuses … its priceless.


Thanks for your telling us - so we can learn more about this car.