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Mike, Mercedes Technician
Category: Mercedes
Satisfied Customers: 39198
Experience:  Tech Expert
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I have a CL600. The car seems to only be firing on 6 cylinders,

Customer Question

I have a CL600. The car seems to only be firing on 6 cylinders, all the time.
I know this is supposed to be a feature of this model that it will do this when criusing down the motorway.
It still has plenty power but it is not running as it should on all 12 cylinders.
Submitted: 3 years ago.
Category: Mercedes
Expert:  Mike replied 3 years ago.
Hello and Welcome..

My name is MIKE - Im happy to help / advise you .

What is the mileage on the vehicle?

What is its service /recent repair history?

Do you have any fault lights / messages on the dash at all - if so , what are they?

Do you have any test equipment at all or is it advise you need generally?

Rgds - MIKE........................................
Customer: replied 3 years ago.

Hi Mike,

I am not with the car at the moment so I will have to get back to you with that information.

Expert:  Mike replied 3 years ago.
No problem at all Shaun..

Do that - and when I receive it , I will get back to you asap thereafter -

Rgds, MIKE.....................................

Customer: replied 3 years ago.

Hi Mike,


Mileage = 88134


Service History = Full service history


Recent repair history = Intercooler oil seal in middle of V12 cylinders.

Plus new ignition modem


Fault lights/messages = Check engine light on


Test equipment = Extremley basic.





Expert:  Mike replied 3 years ago.
Hello there Shaun -

Thank you for the added info..that is very helpful here.

Ok - the "ignition modem" - you mention - that would be the Ign Module.. thats a common fault that will cause misfires on these....

The only thing I would say there - when replacing these parts - dont fit the cheap/ aftermarket parts - they can give as much trouble and lead you round in circles for hours..always use MB parts...

Other that that as above- a common issue on these - is random failure of the coil pack themselves - so that should be a consideration - proper tests done there.

But I note too you have the Check engine light on.. This light being on will mean there will be fault Codes logged on the engine management computers fault log.. so - it needs to have a plug fault code read done Shaun... undoubtedly that will tell you where the issue is for sure - the fault codes will say - coils or such like.

On occasion you can get a faulty Ecu - ( main computer.. the coil "drivers" are in there..) but - the other things inc wiring / connection checks should always be done first.

So other than a basic visual check - to inc checking the spark plugs and coil leads etc - for signs of arcing ( meaning - if arcing ( black track marks ) are found - the parts should be replaced as thats the likely culprit ).. then the starting place then would be to have the Fault Code read done... A tip here would be to use a garage that has "good" test equipment - not basic... as good equipment will tell a lot more than just fault codes.

So thats the way forward on this one now Shaun.. by all means let me know if you need anything more at all as you go.

Kind Rgds - MIKE.

..>> >> > .Meantime..............Please do click on the "OK/ Excellent ratings" for me as that's how Im credited for helping you - Thank you in advance for that...

You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..

Rgds, MIKE.