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Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 23073
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Turbo not activating - done turbo, activator, EGR valve,

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turbo not activating - done turbo, activator, EGR valve, sensor attached linked to EGR.
Customer: replied 6 months ago.
that should read actuator not activator


If you haven't already then check all the high pressure hoses post turbo/s for any split hoses or cracked metal pipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost.

If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues

Also check that the vacuum hose running to the dump /or turbo bypass valve is intact with no leaks as if the dump valve is opening prematurely you'll be losing all your boost

The dump valve is on the turbo boost air (post compressor) side its there to blow off or 'dump' the excess boost pressure you get when you close the throttle ( like just before a gear change)
the important thing with a dump valve is that it seals properly when its not being operated if the valve has a torn seal or a broken spring then it'll blow off before it should and you'll lose boost pressure

this video shows how you can test it

If this is OK then check for air leaks after the mass airflow meter - The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

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Customer: replied 5 months ago.
All of the above I am assured by the garage have been checked still not working - fault code now showing is 2513-1, which apparently is the servo motor situated just underneath the turbo, a big job to get at, and the mechanic does not think it is related to the turbo problem anyway, (having said that the mechanic does not know what the problem is, he has run out of idea's) which of course is why I sent the question to you in the first place, not sure now how to proceed.


in your 1st answer you said the activator ( actuator) had been replaced already?

If this in not the case then yes its possible that its faulty what can also happen is the vanes on the turbo can seize up

so I'd suggest to disconnect the actuator motor from the turbo and then check the the turbo mechanism moves freely under finger pressure

if not then the turbo will need to be stripped and cleaned and the actuator should move in and out when the ignition is 1st turned on

Customer: replied 5 months ago.
The turbo has been tested and it moves freely. The actuator has been replaced. I am told this electrical unit under the back of the turbo has a habit of getting oil in it which eventually causes it to break down. now the garage has it on their estimate for repair as MA642 150 04 94. L1821 SERVOMOTOR. at £149.00. Now I do not know the parts that make up the turbo system. so I am at the mercy of those who do


that servomotor part no. is shown as for the inlet manifold?

so it controls the variable inlet flaps

the turbo actuator motor controls the position of the turbocharger internal vanes that regulate the boost pressure

its the rectangular box on the bottom of the turbo as shown in this image

if it was faulty it would certainly result in a lack of boost pressure

Customer: replied 5 months ago.
does the inlet manifold servomotor have any effect or connection to the turbo system.


not a huge influence

it changes the shape of the torque curve but shouldn't have any effect on the turbo

can you tell me if you've had any fault codes read off and what they are?

Customer: replied 5 months ago.
The first fault code that came up was - 2510-001, which apparently indicated the EGR could be compromised, the turbo,was checked - okay, the EGR was replaced, the Actuator was sent away for rebuild test then refitted, all the pipes connectors tested for leaks, the last item replaced was the sensor, when the car went back into the garage for a none related fault, the diagnostic reading was done again and this time the fault code was 2513-1.hope this helps,


that code does point to the inlet servomotor

as you say it can get damaged by oil dripping onto it

if you want a cheap fix then you could just unplug the motor and fit a 4700 ohm resistor to satisfy the ECU open circuit monitoring

also it looks like Euro car parts keep the motors too a lot cheaper than MB at about £85 quote part number###-##-####/p>

Customer: replied 5 months ago.
okay, I have a little more confidence with the above answer, I will now go back to the garage and arrange for the work to be done hopefully it will fix the problem. pay and smile. cheers Mike

glad to have helped