Replacing Brake Vacuum pump due to code 27e4

[Xgelato]

Can I replace the brake vaccum pump on a e92 M3 by detaching and removing the front left fender liner? And if I replace the vacuum pump, do I have to flush the brake fluid?

Unless it is completely necessary I don't want to remove the master brake cylinder to replace the vacuum pump since it is a longer heftier process.

Would you guys recommend buying it used or new?

https://parts.bmwofstratham.com/a/BM...n/34_1627.html

Part number: 34332283333

Purchase Link: https://www.ecstuning.com/b-genuine-...p/34332283333/

[mapster37]

yes, it can be replaced by removing the fender liner. no need to do brake flush, brake lines should not be opened as part of this repair

[BayE30]

Buy new. But not from ECS.

my price on this pump new is $309 with tax...

EDIT: just found this, https://www.pelicanparts.com/More_In...-2-283-333-M44

[Dpc2u]

I had the same code a week or so after doing my brakes. Started occasionally and then got worse and more frequent after I would clear the code. I also would hear the vacuum pump running a lot more than normal. After a lot of research I changed the pressure sensor located In the vacuum line directly under the master cylinder. If even a few drops of brake fluid drip onto the sensor wire connector it fries the sensor. I would make sure that is not the issue before doing the actual vacuum pump. Have you done any brake work or fluid change/addition recently?

[Xgelato]

No, I haven't done any brake work or fluid change/addition recently. I did notice popping on the screen that a brake fluid change is due for service. But I haven't done it yet. I do hear the Brake vacuum pump a lot.

When I clear the codes, it takes a few days before they come back.

Did you have to remove the master cylinder to change the Sensor?

[Dpc2u]

Originally Posted by Xgelato

No, I haven't done any brake work or fluid change/addition recently. I did notice popping on the screen that a brake fluid change is due for service. But I haven't done it yet. I do hear the Brake vacuum pump a lot.

When I clear the codes, I take a few days before they come back.

Did you have to remove the master cylinder to change the Sensor?

Some say yes, some say remove just the reservoir. I did neither. It is a very tight area to work in. I removed the bolts from the abs block to get a little more clearance and with some wobble extensions and a long screwdriver, just to push the hoses over slightly, was able to get the two torx bolts out. Have a retractable magnet handy in case you drop a bolt. I then used very long needle nose pliers to remove the sensor and position the new one. It is tedious and not an easy task, but doable. Do a search, there are several DIY posts on it. It is a pretty common problem, but the actual vacuum pump failing is much more rare.

You should also make sure you have no cracks in any of the lines causing a slight vacuum leak which can throw the same code.