P0299E6 Error 2019 E400d OM656 engine

[Markha]

I have a 2019 E400d OM656 engine which goes into limp mode occasionally, when you turn off and restart vehicle returns to normal operation. Only happens when driving leisurely (normally with cruise control on) and never when driving harder.

Spoken to a turbo expert who says no point in investigating unless we can get fault to happen to order.

P0299E6 Error code (Boost pressure f turbocharger 1 is too low).

Can anybody give me any guidance?

Mark

 

[AW192]

This is a very common issue unfortunately with the OM656 and has nothing to do with the turbo itself but the vaccum pipes that actuate the turbo
The oil pump and the vaccum pump are built into one in these engines which causes the seal between the oil and vaccum side to degrade over time allowing oil into the vaccum system
Once this occurs thats when the symptoms your car is displaying happen theres a tsb out for this also
I will find it tomorrow and link it
I also had to chase the same issue with mine i ended up removing the selenoids and replacing them aswell as the oil pump and cleaned out all the vaccum lines with a lot of brake and parts cleaner

 

[runju26]

Is this an engine out job to replace the pump?

 

[AW192]

Is this an engine out job to replace the pump?

Yeah engine out as the timing chain has to be removed which are at the back i did try splitting the box whilst in the car to see if maybe there would be enough space but it is quite tight

 

[runju26]

Yeah engine out as the timing chain has to be removed which are at the back i did try splitting the box whilst in the car to see if maybe there would be enough space but it is quite tight

Oh…. I’m assuming they normally fail at higher miles?

 

[AW192]

Oh…. I’m assuming they normally fail at higher miles?

These have two types of failure
Partial failure which causes the symptoms that my car had and the car above in this thread
And these are reported to happen as early as 40k miles
My car had 57k when the issue started full merc service history every 8k miles
And then there is complete failure which leads to complete loss of braking power as the vaccum pump also controls the braking system its a very bad design by MB

 

[runju26]

Damn…. The last bit sounds dangerous, I guess I better start sticking to the speed limits of 2.0 mph lol

Then again tough to drive fast in London with a maxton kit on

 

[runju26]

BTW can you visually check if this is failing, or does it have to be a limp mode symptom?