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So I have the W211 E240 Avantgarde, I love it to bits - I know this has possibly been mentioned by my issue is different - I don't have the usual (STOP) display on the cluster, Instead I have (reduced braking power - Longer stopping distance) my code it throws out is not the C249F it is the C269A Related to Hydraulic Fault: Brake operation unit (BOU) as per the diagnostics - I don't believe it is related to my SBC Pump, as if I don't go rough and pump the brakes and drive normally paying attention NOT TO PUMP the brakes I don't get the message at all and all is normal, If I do pump them the message appears.. so I'm concluding for myself, that's why I need your guys help, that it is electrical? and not the basic 300 000 brake pushes which codes C249F and no - one where I am understands me, also I don't think the switch, but maybe ? but anyhow if I pump hard my brakes go right down, but normal driving brakes are perfect, It has new disks, new Brake Pads and new tires. I bought the car recently, so perhaps I don't know if they fitted it the right was by disconnecting first the SBC Pump that I get this Message ? Please help me narrow this down and get this sorted please someone??
Maybe try the brake switch ($10)? That is the first thing I would do. How many miles does your car have? I carry an extra brake switch in my car just in case!!
C269A if I don't go rough and pump the brakes and drive normally paying attention NOT TO PUMP the brakes I don't get the message at all and all is normal, If I do pump them the message appears.
C269A = hydraulics fault brake operating unit (BOU). See attachments for current part # and tandem master cylinder details. As a first attempt replace brake fluid and clear codes. If this fails I suggest replacing unit (master cylinder).
Excellent - Thanks for this, I have booked the car in to bleed and flush out the Fluid in the braking system to restore pressure - I will keep you updated - THANK YOU
Hi - I have just heard back from Mercedes and they said the unit (master cylinder) is leaking, they want to replace the whole unit, I cannot afford that - surely it can be fixed ? as the braking is fine on the car, maybe a slight leak, I know its not good but can it be repaired the leak or changing the rubbers etc.
The master cylinder on your car is not hydraulic, it is electric. When you depress the pedal you are literally pushing against a sensor that communicates to the SBC via sensor B37/1 to activate solenoids to apply pressure to the appropriate wheel calipers. Tactile feedback is provided by a spring and rubber puck in the master cylinder.
Konigstiger provided the part number. Search online for a replacement at a lower cost, then find a good indy to replace it. This is your life and the lives of your passengers. Do not try to save money on brakes. Heck, I'd be willing to bet that your medical deductible is larger than the cost of this repair. And your medical deductible would be in addition to totaling your car.
I have found one with guarantee and I will have a specialised guy change it for me - but SBC has to be deactivated ? and also once all done, as the unit will work, by depressing the pedal, I shouldn't get the error code again, or must the brakes be bled only by Mercedes after the unit is replaced?
You can deactivate the SBC unit for brake service a few ways. Use MB/ Chrysler Star or Xentry computer system that dealers and some Indy's have. Use an iCarsorf MB II diagnostic tool or closely follow manual SBC deactivation procedures. These are typically enacted when replacing the brake pads. Not sure if this holds true for replacing the Brake Operating Unit. Maybe some one else will chime in.
Note: If not mentioned in the videos, the keyless GO fob (if equipped) needs to be far away from vehicle so as not to inadvertently activate the SBC system while servicing the brakes
I've been rebuilding MC several times in my life, when living in Europe, but in last years in US you will not find parts for rebuild, so you have to get whole unit.
I am very skeptic about "guarantees" and "rebuilds" offered in USA, so my advise is to bite the bullet and spend money on new one. Husker offers MB parts for much less than anybody else.
You will sleep much better.
11-22-2017, 07:11 AM
