Deadly SBC failure - warranty extension in USA and Canada

[Botus]

the brakes on Mercedes are interesting to say the least...

On the 221 at 50 k miles - pah ! I had to replaced seized calipers. I fitted new genuine front calipers, discs and pads from merc garage. The pedal feel before and after was exactly the same (awful), and funny enough the exact same affliction is there every time I drive my fathers 211 but with SBC, its worse.

They both exhibit one characteristic under braking that makes it more unpleasant and harder to modulate than any other brand of car I've driven. I would put the cause down to the passion that is the appalling driving you see demonstrated on autobahns every day were it not for the fact I never experienced it on any of my 3 BMWs (two 535 petrol and one 335d).

This odd characteristic is there every time you brake. When slowing down the pedal is the usual averagely vague nothingness then I guess as the disc and pad temperature reaches a certain point the brakes suddenly wake up and grab, meaning you have to continually modulate pedal pressure to brake smoothly and consistently. Its as if the pad compound is set for maniacs trying to brake from 120mph to 40 every one hundred meters - which is how the drive in Germany. But its not something I need in my life, nor have ever experienced on any other brand of vehicle.

 

[Philedge]

This failure is totally unexpected, yet deliberately engineered in to the car in software!!!.

SBC is a ridiculous system giving hideous pedal feel, silly noises and no sensible benefits at all - if it did, it would be used by other manufacturers and Mercedes themselves wouldn't have ditched it...

As I understand it MB dropped SBC because of poor customer perception. This may well have been amplified by wild statements made on internet forums such as the service counter limit causing total brake failure or that the units software is programmed to fail

 

[V6Matty]

This odd characteristic is there every time you brake. When slowing down the pedal is the usual averagely vague nothingness then I guess as the disc and pad temperature reaches a certain point the brakes suddenly wake up and grab, meaning you have to continually modulate pedal pressure to brake smoothly and consistently. Its as if the pad compound is set for maniacs trying to brake from 120mph to 40 every one hundred meters - which is how the drive in Germany. But its not something I need in my life, nor have ever experienced on any other brand of vehicle.

Have to admit I’ve never felt that with any of my Mercedes, my previous X5 was also the same brake feeling as my Mercedes, that was the 4.6IS so had the upgraded callipers and disks, I’d go as far as saying that if pushed the 211 SBC brake set up was better stopping power than almost anything I’ve driven before, including a couple of porkies with carbon ceramic disks.

 

[Botus]

I'd say my perception of SBC is poor. My odd brakes is silly enough, but the effect on my father's car (with SBC) and not much happing then out of nowhere with exactly the same pedal pressure, extra braking turning up is inconsistent.

On his, the bonus braking is in the region of 30% extra and comes and goes during the same 50 metre gentle stop which is ridiculous. I estimate mine gets 20% out of nowhere. But always at the same point during a given braking manoeuvre and I got used to it. You just have to lift the pedal 15mm at 40% into a given stop (or you end up stopping 20m short of where you intended).

Whereas the SBC one is more like press a lot, car starts to slow as expected, pads warm up and get grabby, so you lift a bit, then the bonus stopping declines you have to press harder to maintain the new higher rate (or look like you can't drive), they warm more and brake even more till you're going to stop short so you have to release, then they seem to not do enough and you ride this wave of random deceleration till rest and or the passengers complain.

Mine has two distinct phases, cold pad, slows as expected, pad warm brakes grab windscreen comes towards you so have to release, the SBC makes around 5 random phases (probably based on the colour of your neighbours washing that day). Basically a random effort every time. Of course if it was your daily driver you could subconsciously work around it, but one shouldn't have too.

I would like to point out, I'm a fully qualified vehicle tech and I think both cars have brakes in A1 condition with no faults other than rust prone high iron standard discs and sporty standard compound brake pads. Fluid (Mercedes) in mine is 6 months old and 12 months old on my father's. Before this I've never owned a car where discs go rusty after a gentle shower.

 

[LostKiwi]

Fundamentally SBC is simply an electronically controlled brake servo and operates on a similar principle to ABS (which no one seems to complain about).
Personally I have never felt the braking feel was anything other than excellent, whether pressing on (as last year in the Highlands) or just cruising about town.

It also seems much maligned by internet scare stories yet I've never heard of anyone with a correctly maintained system having any issues.

 

[Botus]

Just thinking, I've owned two heavy omega's both had excellent, very consistent and powerful brakes that were a joy to use. Between them and the 221 was the 335d and I remember now that had a silly unstable set up that made it dangerous.

Its rear end was unstable when slowing down, to the point where I would have it recalled. It was not per say the rear brakes but a combination of the silly gearing with badly judged ratios and a battery regen system. They decided for an economic / emission idea that on a closed throttle it would decide this was the best time to push lots of current at the battery by implementing some odd engine braking idea to charge the battery.

Under hard stops the back end would breakaway, which was "entertaining" if you were cornering at the same time. Or just plain unpleasant if trying to come to a gentle rest at the lights.

 

[AMGeed]

My experience of a car with SBC braking was nothing but positive. Excellent feel and superb stopping capabilities.
It saved me once on the M3 when someone pulled out without looking. It's annoying that the pump in itself is grouped with discs pads and tyres etc as being a consumable item and needing replacement at some time during the car's life.

Many early models that had it fitted, had the pump replaced under warranty until MB decided around 2012 that the customer (in the UK) would foot the (expensive) bill and warranty replacements would end. A few lucky owners with full main dealer service history were lucky and got a free or heavily subsidised replacement.
Fortunately there are companies, Johnny SBC forum member for one), that will now strip down and recondition your pump and even reset the actuations if the correct codes are displayed.
I'd imagine that is exactly what is done with the pumps exchanged at main dealers and the pumps are returned to Bosch for reconditioning.

I will say the traditional brakes on my W212 E63 are absolutely spot on and equally as efficient as my E55 with SBC. Just a pity the discs and pads are a bit pricey. Still, that is a given if you own an AMG. Parts can be expensive.

 

[LostKiwi]

My experience of a car with SBC braking was nothing but positive. Excellent feel and superb stopping capabilities.
It saved me once on the M3 when someone pulled out without looking. It's annoying that the pump in itself is grouped with discs pads and tyres etc as being a consumable item and needing replacement at some time during the car's life.

Many early models that had it fitted, had the pump replaced under warranty until MB decided around 2012 that the customer (in the UK) would foot the (expensive) bill and warranty replacements would end. A few lucky owners with full main dealer service history were lucky and got a free or heavily subsidised replacement.
Fortunately there are companies, Johnny SBC forum member for one), that will now strip down and recondition your pump and even reset the actuations if the correct codes are displayed.
I'd imagine that is exactly what is done with the pumps exchanged at main dealers and the pumps are returned to Bosch for reconditioning.

I will say the traditional brakes on my W212 E63 are absolutely spot on and equally as efficient as my E55 with SBC. Just a pity the discs and pads are a bit pricey. Still, that is a given if you own an AMG. Parts can be expensive.

If you factor in s lifespan of 100k miles getting someone like JohnnySBC to rebuild it comes out at 0.5p per mile cost (that's Johnny doing everything). If you take the pump out and refit yourself it's under 0.4p per mile. Hardly onerous.

 

[Botus]

DVSA Thank you for your reply.

I do have a vehicle impacted by this. My father’s Mercedes has this feature. Reg. xxx VIN. WDB21102xxx However my concern is not over this vehicle, it is the dangerous system fitted to thousands of Mercedes cars that matters. I note there is a TSB out for mk4 Ford Focus’ with a similar issue 19B36 - FOCUS - ELECTRONIC BRAKE BOOSTER – SOFTWARE. So it seems another manufacture is building dangerous vehicles implementing similar hardware?

Please note I am a fully qualified Motor Vehicle Tech and I was just replacing the Aux battery that provides the SBC actuator with power in the event of emergencies. It was whilst investigating this I became aware of this exceptionally dangerous and badly implemented system – which in other countries has been brought to the attention of owners and systems implemented to better mitigate the risks.

Please note - In the event of SBC components reaching “a software derived end of life value”, it leaves the vehicle only with non assisted Front brakes. I believe most owners hitting this milestone have NOT had any warnings about this prior to effectively total brake failure.

I do not know if you have attempted to stop vehicle's without the servo assistance on the braking system, but it’s almost impossible. Most vehicles operate with a conventional vacuum servo assistance braking system, giving it PAB (power assisted braking). And should the engine derived assistance stop (powered by a pump on diesels or inlet vacuum on petrol) the driver is left with 3 to 5 pedal actuations before assistance is no longer available and in all cases has brakes to all four wheels operational. A further point on this failure mode is that its progressive with assistance declining until it’s likely a driver will stop before total failure. Whereas the Mercedes SBC system is an instantaneous failure, suddenly leaving the driver with only braking to two wheels.

Please can I suggest you test the how dangerous a vehicle is after losing (braking) assistance before making judgement of whether we want lots of Mercedes cars on the roads without it? A simple test (for conventional servo assisted braking) would be to stop on a very small slope – just enough for the vehicle to roll on its own. With the engine off, pump the brake pedal 10 times till you feel the pedal go stiff as the assistance is completely removed. Now carefully release the park brake and when travelling at no more than 2 mph (two) try to stop the vehicle using the normal foot pedal. I expect you will NOT be able to bring the vehicle to rest.

As for messages reaching the driver to warn of the need to maintain the braking system. I do not believe on these cars, there is any message (it’s possible later software did change this behaviour (i don’t know) but I’m sure many vehicles would never have received an update.

Sadly this is not unusual there is a dangerous lack of safety first attitude prevalent in the motor industry and many systems are not built fail safe. With virtually all vehicles since 2004 running some software based systems, it is virtually unheard of in a car prior to 2010 ever having software updates applied on any part of the car.


For example

1) I had a Aug 2007 built BMW 335d, by Jan 2014 not a single module of the 39 fitted had ever had any updates applied. Interesting BMW do have the equipment to correctly re flash all systems in the car in one software session (an i-level update) but they don’t do it on cars pre 2010. When I sought to get my vehicle updated the dealership tried on 6 separate occasion to refuse to carry out the work. When Sytner High Wycombe (one of the UK largest Franchised BMW dealerships) did complete the work they admitted it was only the second car they had ever completed this work on.


2) Another example. On my Mercedes S class it was in at Hughes Beaconsfield (a well respected Mercedes dealership) prior to my purchasing it and again no software updates where applied. I subsequently had what I believed was all the software updated in Aug 2014 at Greenoaks Slough. However it turns out that they only updated the Comand hifi system. Even though multiple updates to safety systems were available, these were never applied to the vehicle by either of the two major dealerships in this part of the country.


3) Airmatic suspension systems on other Mercedes vehicles Fail dangerous. Even though it could easily be altered to fail safe in a 10 minute software update. My S class has air suspension at all four corners. Even though it’s been fully serviced by an independent specialist Mercedes garage, and I have personally lubricated all the suspension level sensors regularly, these seize up and can snap leaving the car in a dangerous state and without warning. Once the level sensor breaks the vehicle rapidly becomes dangerous and un-roadworthy.

This happened on my vehicle (without any warning) after the rear level sensor on mine broke (a common issue on Mercedes cars). In this situation the car stupidly dumps all air and collapses the suspension until its totally unsafe. This can happen at any road speed and this dangerous situation is purely because a very basic and badly written fail dangerous piece of software is used.

The specific failure mode is because the under engineered and badly protected (from road dirt) link rod seizes and snaps off. At this point the software could easily say no signal from level sensor maintain current air volume. (This air lock out feature is in the car and is part of the system already - it’s just NOT implemented in this failure mode). With the link rod having broken, the suspension level sensor arm falls down and indicates to the car that its ride height is too high. So it bleeds air out to reduce the ride height until the vehicle is on the ground with no suspension movement left. Fail safe would be to simply say in software that either, no information is being received by the level sensor or that its outside its normal operating range, lock air in system and throw error on the instrument cluster. This should be a vehicle recall to implement fail safe code to both front sensors and the one at the rear.

Furthermore on a Mercedes each module is a one off update and with 50 separate computer modules (on my car) it is time consuming – thus far less likely updates are ever carried out. Until recently my 2006 car it had only ever had engine and gearbox updates applied by main the dealer network.

With that brief introduction I do not share any confidence that Manufacturers either address safety issues, or ensure dealerships or owners are aware of and apply safety critical enhancements to vehicles


Regards

 

[Philedge]

Please note - In the event of SBC components reaching “a software derived end of life value”, it leaves the vehicle only with non assisted Front brakes.
Regards

When the service counter hits its limit, it puts a white visit workshop warning on the dash, no degredation of braking performance.

Dont know why youre persisting with this wild claim of total/substantial brake loss, as needlessly scaremongering over SBC has the potential to devalue your dads car if he ever tried to sell it.

 

[LostKiwi]

I believe most owners hitting this milestone have NOT had any warnings about this prior to effectively total brake failure.

I have covered this before.
Person A buys the car and gets a white Service Brake Visit workshop message.
They go on eBay and find a kit that resets the SBC pump actuator count or disables it.
They then sell the car to person B who is blissfully unaware the counter has been tinkered with. The pump continues to operate until it hits a terminal failure caused by for example brushes wearing out.
Person B then fills the internet with scare stories about how the pump failed with no warning when in reality the pump had given a warning which was then disabled (much like the old game of removing earning lamps from ASR/ABS/EML etc).
Whilst I don't doubt there will be instances of genuine failure with no warning I firmly believe they will be a very small number.
If you're so concerned simply replace the pump or have it refurbished. Treat the pump as a consumable. As already noted previously the pence per mile cost of a pump is buttons.

Your Airmatic 'fix' won't work. In order for it to recognise there is a sensor failure it needs to know what pressure exists in each bag (more sensors - you already complain about the number of sensors). You clearly are getting a signal as that's what is telling the ECU to release pressure.
The simple fact yours rusted through and failed actual suggests poor maintenance. A visual inspection and wiggle to verify structural integrity would have found the issue before it failed, if it had been done.
I'd take it up with whoever last serviced it missing an obvious issue.

 

[Botus]

I have covered this before.
Person A buys the car and gets a white Service Brake Visit workshop message.
They go on eBay and find a kit that resets the SBC pump actuator count or disables it.
They then sell the car to person B who is blissfully unaware the counter has been tinkered with. The pump continues to operate until it hits a terminal failure caused by for example brushes wearing out.
Person B then fills the internet with scare stories about how the pump failed with no warning when in reality the pump had given a warning which was then disabled (much like the old game of removing earning lamps from ASR/ABS/EML etc).
Whilst I don't doubt there will be instances of genuine failure with no warning I firmly believe they will be a very small number.
If you're so concerned simply replace the pump or have it refurbished. Treat the pump as a consumable. As already noted previously the pence per mile cost of a pump is buttons.

Your Airmatic 'fix' won't work. In order for it to recognise there is a sensor failure it needs to know what pressure exists in each bag (more sensors - you already complain about the number of sensors). You clearly are getting a signal as that's what is telling the ECU to release pressure.
The simple fact yours rusted through and failed actual suggests poor maintenance. A visual inspection and wiggle to verify structural integrity would have found the issue before it failed, if it had been done.
I'd take it up with whoever last serviced it missing an obvious issue.

the idea you suggest of how a failure on the SBC could happen outside a vehicle users knowledge is feasible. Do we know if these cars left the factory with this error message in place? The USA document refers to part of the fix being a software update. My concern is this never / rarely happens on UK cars - and what does this update bring?

I dispute the point you make about a safety fix on Airmatic. Prior to a sensor failure / normal range failure, it would know the suspension unit is inside a safe usable height. So locking out air movement would be better than the dangerous set up it has now.

Before I had a new pump and relay fitted two years ago, I believe it popped the main fuse to the pump and thus instigated this lock out feature and it lasted for 6 months - without informing the driver there was anything wrong at any point. During this time the only thing I noticed was the suspension raise feature no longer did anything ! - however, it never informed the driver there was anything wrong and perversely the car seemed to drive better than it ever had during this period. So I tolerated a feature I seldom used "appearing to do nothing" for the day to day benefits of what seemed a better judged set up (only 6 months down the road with an odd very high offset 300kg loading did the ride height alter in one corner (which leveled out inside 1 mile and two trips later threw an Airmatic error message).

And just in case they did update and bring better warning / better failure mode fixes, mine was updated this year - before the rear height sensor failure, so they didn't resolve this easy fix as of Aug 2019.

Furthermore to suggest my suspension failure was a lack of correct maintenance, would be to suggest a well known, well respected, forum supporting indepenant garage failed to inspect / lubricate (which they tell me is not the case) and I can definitely say I attempted to alleviate this known failure point myself by regular lubrication,

 

[V6Matty]

The update was to extend the pump actuations count, it was originally set low as a precaution but after finding the pumps themselves were fine they updated the software and extended the limits.
One thing you’ve missed is that there was a recall for the 211’s with SBC, a known issue where the wiring for the unit rubbed on another component and shorted things out, a bracket was added and some dampening added to the pump itself, part of the recall was also the above software update so in all likelihood most cars have had it.

 

[Botus]

thanks - very useful

 

[Botus]

its a shame this service isn't a bit more reliable …. (most vehicles I check come up with this message)

https://www.gov.uk/check-vehicle-recall

We don't hold information about manufacturer's safety recalls for MERCEDES-BENZ E xxxx xxx.
To find out if your vehicle has any outstanding safety recalls, contact a MERCEDES-BENZ dealership.

 

[V6Matty]

I found the same when I bought my 211, rang a dealer and they confirmed it had been done and also printed out the service sheet and sent it to me.

 

[Botus]

needlessly scaremongering over SBC has the potential to devalue your dads car if he ever tried to sell it.

his life is worth a lot more than the car,

 

[malcolm E53 AMG]

Whoever decided to introduce SBC into MB cars made a grave error but I understand the urge to design something ‘new and better’, if all Mercedes cars were maintained throughout their life at franchised dealers they may have got away with it but life isn’t that simple hence why it was dropped.

 

[Philedge]

Whoever decided to introduce SBC into MB cars made a grave error.

I wouldnt class the errors they made as a grave ones.

First error was to under estimate the number of drivers that routinely dab the brakes whilst driving and rapidly rack up the service counter to the point where the limit is reached, regardless of mileage.

Second error was to release the first version of SBC with an overly conservative service counter limit. The conservative limit would have ensured an unnecessarily high volume of early "failures" when in fact the units replaced and returned were perfectly serviceable which led to the increase in service counter limits. Had they covertly monitored the SBC units condition against operations, then they may have been able to increase the service counter limit without having all the early and premature "failures"

The biggest problem with SBC is that for most users they wouldnt even have noticed the benefits the system provided and not appreciated that SBC likely converted many a potential accident into a near miss

 

[Botus]

the only benefits of my fathers car with SBC is

1) odd brake pedal feel,
2) odd noises from the module
3) a stupid penchant to stand on the brakes when you don't want it too (because the current drivers reaction time isn't as slow as many drivers they clearly thought needed help)

never had any of those issues on a car with conventional servo assistance