E92 M3 - Vacuum sensor brake booster plausibility... TWICE!
Discussion
Will try to make a long story short.
A few months ago I took my 2011 M3 to ‘garage A’ as I had a sticky calliper. They quickly identified it and installed a new calliper, two new pads, and changed the brake fluid. All sorted and I’m happy.
A few weeks later I get the 27e4 “vacuum sensor brake booster plausibility” error (using Carly) and the car goes into limp mode. I restart the car and it goes away.
The problem comes back, gradually becomes more common, until the car is permanently in limp mode.
After a bit of Googling I discover that the M3’s vacuum sensor is located right under the brake fluid reservoir, and if you’re not careful, it’s very easy to spill brake fluid on to the sensor... which eats into it and gradually kills it.
I speak to garage A about this and after a bit of back and forth they agree to replace the sensor at cost price (£145 or so) with no labour. When I pick the car up, they show me the sensor and it has no fluid on it at all... it’s completely clean. So we put it down to a coincidence and I’m left happy that they did it for such a good price.
However, fast forward a month or two (last weekend), I pull out of my drive and the car goes into limp mode and gives me the same error. As the same problem has come back, I decide to book it into a different specialist... garage B.
Garage B can’t get the error to come back straight away, because it’s intermittent... but eventually they do and they call me and confirm it is indeed the same 27e4 error.
They are replacing the sensor again as we speak and checking the reservoir and the rest of the brake system for leaks (at my request)... I’ve seen no drips on my drive nor do I think there’s any leaks, so I’m guessing this isn’t the culprit, but I’m out of ideas.
My question to PH is have I just been really unlucky here and had two sensors go pop in the space of a few months or is there something else that could be causing this?
Could garage A have cleaned the old sensor to cover their tracks? Could they have provided me with a dodgy second-hand sensor?
I’ll be paying garage B full whack for the part and labour so I don’t want this problem to come back again.
It’s a relatively uncommon problem with this car so to have the same error in such a short amount of time seems a bit odd to me.
A few months ago I took my 2011 M3 to ‘garage A’ as I had a sticky calliper. They quickly identified it and installed a new calliper, two new pads, and changed the brake fluid. All sorted and I’m happy.
A few weeks later I get the 27e4 “vacuum sensor brake booster plausibility” error (using Carly) and the car goes into limp mode. I restart the car and it goes away.
The problem comes back, gradually becomes more common, until the car is permanently in limp mode.
After a bit of Googling I discover that the M3’s vacuum sensor is located right under the brake fluid reservoir, and if you’re not careful, it’s very easy to spill brake fluid on to the sensor... which eats into it and gradually kills it.
I speak to garage A about this and after a bit of back and forth they agree to replace the sensor at cost price (£145 or so) with no labour. When I pick the car up, they show me the sensor and it has no fluid on it at all... it’s completely clean. So we put it down to a coincidence and I’m left happy that they did it for such a good price.
However, fast forward a month or two (last weekend), I pull out of my drive and the car goes into limp mode and gives me the same error. As the same problem has come back, I decide to book it into a different specialist... garage B.
Garage B can’t get the error to come back straight away, because it’s intermittent... but eventually they do and they call me and confirm it is indeed the same 27e4 error.
They are replacing the sensor again as we speak and checking the reservoir and the rest of the brake system for leaks (at my request)... I’ve seen no drips on my drive nor do I think there’s any leaks, so I’m guessing this isn’t the culprit, but I’m out of ideas.
My question to PH is have I just been really unlucky here and had two sensors go pop in the space of a few months or is there something else that could be causing this?
Could garage A have cleaned the old sensor to cover their tracks? Could they have provided me with a dodgy second-hand sensor?
I’ll be paying garage B full whack for the part and labour so I don’t want this problem to come back again.
It’s a relatively uncommon problem with this car so to have the same error in such a short amount of time seems a bit odd to me.
I might be talking rubbish here but I had this problem on mine a couple of years back & when I was looking into it I'm sure I read that the message can relate to the vaccum pump itself, which I believe is located somewhere behind the near-side front wheel arch liner. Again, I could be wrong but it might be something to check.
Incidentally, my problem was the sensor which I replaced & has been fine since.
Cheers,
Ben
Incidentally, my problem was the sensor which I replaced & has been fine since.
Cheers,
Ben
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