Replacing Brake Vacuum Pressure Sensor

[deansbimmer]

Originally Posted by ns2000x

Unfortunately all back together and I still get the 27E4 code and limp mode. When I pulled the old sensor out it was still under vacuum so I don't believe the hose is compromised. What is next for me to check???

Make sure the three check valves are functioning correctly and verify the pump is working correctly. Check also for wire damage and shorts.

[ns2000x]

Originally Posted by deansbimmer

Make sure the three check valves are functioning correctly and verify the pump is working correctly. Check also for wire damage and shorts.

Thanks! The wires looked OK, but I didn't unwrap them to check. I'll research how to verify the check valves, thank you for the tip.

I guess I should listen for the pump upon start up. I'll check RealOEM for the part number and start shipping for a pump price.

[deansbimmer]

Originally Posted by ns2000x

Thanks! The wires looked OK, but I didn't unwrap them to check. I'll research how to verify the check valves, thank you for the tip.

I guess I should listen for the pump upon start up. I'll check RealOEM for the part number and start shipping for a pump price.

I have all of these related parts used if it can help.

[M3MPH1S]

Originally Posted by ns2000x

Yesterday I replaced the sensor. I also unbolted the ABS module and shifted it a tad, don't know if it made any difference. My saviour was LONG needle nose pliers, and I think just blind luck positioning the new sensor.

Unfortunately all back together and I still get the 27E4 code and limp mode. When I pulled the old sensor out it was still under vacuum so I don't believe the hose is compromised. What is next for me to check??? It's been about 7 months now my car is half useless...

Cheers

Did you clear the code first? If not, try that. You purchased the replacement sensor NEW correct? The only other thing I can think of is if the actual pump motor is bad, but I'm almost positive that's a different code (although the pump motor feeds straight into the vacuum line that this sensor is monitoring). After that, you could check for faulty ABS due to air in the system? But that most certainly would be a different code.

[M3MPH1S]

Originally Posted by deansbimmer

I have all of these related parts used if it can help.

Can confirm, I ended up buying the sensor new for peace of mind, but bought a used pump from deansbimmer and installed it just in case

[ns2000x]

Originally Posted by M3MPH1S

Did you clear the code first? If not, try that. You purchased the replacement sensor NEW correct? The only other thing I can think of is if the actual pump motor is bad, but I'm almost positive that's a different code (although the pump motor feeds straight into the vacuum line that this sensor is monitoring). After that, you could check for faulty ABS due to air in the system? But that most certainly would be a different code.

Yes I cleared the codes was all happy...for a moment. Went for a spin and then ping. Checked and same code.

I used a new sensor yes, from ECS. Hmm I’ll dig around to see see what the error code usually is for the pump itself before ordering a replacement. It’s almost $500 USD, for a pump shipped to Canada so will see if I can pinpoint first.

Thanks for the help!

[M3MPH1S]

Originally Posted by ns2000x

Yes I cleared the codes was all happy...for a moment. Went for a spin and then ping. Checked and same code.

I used a new sensor yes, from ECS. Hmm I'll dig around to see see what the error code usually is for the pump itself before ordering a replacement. It's almost $500 USD, for a pump shipped to Canada so will see if I can pinpoint first.

Thanks for the help!

Damn. Well definitely check with deansbimmer for a used pump first.

[ns2000x]

Originally Posted by ns2000x

Yes I cleared the codes was all happy...for a moment. Went for a spin and then ping. Checked and same code.

I used a new sensor yes, from ECS. Hmm I’ll dig around to see see what the error code usually is for the pump itself before ordering a replacement. It’s almost $500 USD, for a pump shipped to Canada so will see if I can pinpoint first.

Thanks for the help!

Replaced the pump too. Was good that night, cleared the ever present "Increased Emissions" CEL, and the 27E4 code was gone. Next day, right back as soon as I head down the road. Limp mode, same code.

Knowing I still have the ICV, and throttle actuators to look forward to failing I'm beginning to get the impression the E90 M3 is plagued with gremlins and I might lose the enthusiasm I had on day one to garage her and keep it indefinitely as the last NA M. I haven't even cracked 115,000 km (~72k miles) yet.



Combined with the death plummet in value of my 2017 i3, I'm seriously questioning why I have an F15 X5 inbound as my 3rd BMW...

</RANT>

Apologies.

[Mpower04]

Originally Posted by ns2000x

Replaced the pump too. Was good that night, cleared the ever present "Increased Emissions" CEL, and the 27E4 code was gone. Next day, right back as soon as I head down the road. Limp mode, same code.

Knowing I still have the ICV, and throttle actuators to look forward to failing I'm beginning to get the impression the E90 M3 is plagued with gremlins and I might lose the enthusiasm I had on day one to garage her and keep it indefinitely as the last NA M. I haven't even cracked 115,000 km (~72k miles) yet.



Combined with the death plummet in value of my 2017 i3, I'm seriously questioning why I have an F15 X5 inbound as my 3rd BMW...

</RANT>

Apologies.

Any update on this? Did you replace just the sensor or also the lines it comes with as well? I recently got the 27E4 code as well. Looks like signs of brake fluid going over from the reservoir at one point so I'm assuming the sensor got a little on it. Auto logic says "pump is not running" so I went ahead and ordered the sensor as well as a new pump.

[JOHNNY-5]

This thread really helped me out. Reading everyones post and using all the tips. I was really dreading this as I have big hands and looking at the area I needed to access.

Glad to say, using a wire coat hanger, an extended flexible magnetic attachment, and a long flathead screw driver I was able to remove and reinstall the sensor in about 5 minutes.

The good part? Never had to put my hands in that little area to get scratched up.

[mvolps22]

Reviving this thread, I did not get a check engine code or limp mode but on occasion my brake pedal is so firm it can't be pushed down and my car won't start; I think because it doesn't know the brake is being pushed. Could this sensor be the culprit? If I wait 15 to 60 minutes the car will eventually just start working. The car could be sitting overnight or it has happened while getting gas. No trouble codes.

[WAKman]

Originally Posted by ns2000x

Yesterday I replaced the sensor. I also unbolted the ABS module and shifted it a tad, don't know if it made any difference. My saviour was LONG needle nose pliers, and I think just blind luck positioning the new sensor.

Unfortunately all back together and I still get the 27E4 code and limp mode. When I pulled the old sensor out it was still under vacuum so I don't believe the hose is compromised. What is next for me to check??? It's been about 7 months now my car is half useless...

Cheers

Did you ever find out what the problem was?

Terry

[ns2000x]

Originally Posted by WAKman

Did you ever find out what the problem was?

Terry

The vacuum pump had failed, and blown what I recall was fuse #69 (was listed under “fuel system” and I looked up via a wiring diagram). Finding this blown fuse was the crux of all troubleshooting. So new sensor, new vacuum pump and continuing problem (obviously) until the appropriate wiring diagram was able to lead me to the mislabeled fuse.

Honestly I would have saved time if I pulled every fuse one by one had I not had the wiring diagram of you add up all the head scratching.

[raceyBMW]

Originally Posted by ns2000x

The vacuum pump had failed, and blown what I recall was fuse #69 (was listed under “fuel system” and I looked up via a wiring diagram). Finding this blown fuse was the crux of all troubleshooting. So new sensor, new vacuum pump and continuing problem (obviously) until the appropriate wiring diagram was able to lead me to the mislabeled fuse.

Honestly I would have saved time if I pulled every fuse one by one had I not had the wiring diagram of you add up all the head scratching.

You sir are a genius. Like you I had the hard brake pedal, except mine was happening while at the track .. not a fun experience, felt like I lost brake boost, which looking back I essentially did.

Then a few days later the 27E4 CEL came on, limp mode home at 35mph.

Read threads that said it was the brake vacuum sensor, ordered it and installed. Cleared code and took the car back out and after about 30 seconds, boom, CEL again..shit


Back in the garage. Banging my head on what to do next I ran across your post and the note about the fuse, so I figured what the hell is worth a shot. Well I don't have a fuse #69, so just started pulling all the 60s out and sure as shit, #67, 20amp fuse is blown. Replaced it, cleared codes again, and seems good to go now. A thousand times thank you sir, not sure how long it would have taken me to figure out a blown fuse could cause a CEL. I'm betting the sensor was still bad and caused the fuse to blow, several times I let the brake fluid run over while switching to the track pads.

So to summarize, if you have 27E4 & replaced your sensor and still have codes, check your fuses,l either #67 or #69. Hell, maybe check the fuse first, maybe it doesn't need a sensor at all.

[ns2000x]

Originally Posted by raceyBMW

So to summarize, if you have 27E4 & replaced your sensor and still have codes, check your fuses,l either #67 or #69. Hell, maybe check the fuse first, maybe it doesn't need a sensor at all.

Excellent resolution. I’m glad you found my post and it hopefully saved you a little headache 😁

[raceyBMW]

Update: Still popping #67 fuse, not sure why. Next step is to study the electrical diagrams and see what else in the system could be causing it.

That said, replacing the fuse does make the car run fine without having to touch the sensor again.

[ns2000x]

For me it was the original vacuum pump that had failed, not the sensor. Convinced of it!

I picked up a used one from ECS. It’s in a box still after it didn’t solve the issue (because I never replaced the fuse) and I have a new pump in now (which did nothing until I got the fuse diagram idea).

[Adi123]

It's a 15 $ fix! Got the sensor out very easily. Remove the torxscrews on the sensor, unbolt the ABS and make some space. Pull the sensorcable and you got it in your hands!

I checked the numbers on my pressure sensor and found a MAP sensor from a Z4 with the exact same number on eBay for 15$ (besides the production date). Immediately I heard that the pump stoped working overtime. Have been driving it for 3 days now, no codes, no limpmode

[krapnoj]

Just to add to what everyone has posted, I was having same issues for a week. Everytime I got near 4k RPM car would go right into limp mode. I had my brake fluid flushed by BMW several months ago and then I did my own rear brake pads couple weeks ago. She ran fine just until this week and all of sudden car is handicapped.
I have the Turner Stage 2 tune so I was able to see the consistent code of 27E4 coming up each time.. Noticed the constant buzzing noise coming from the brake reservoir area that was never there before and then noticed the brake fluid well above the MAX fill line..

Seems like same problem as everyone else, the brake vacuum sensor. I noticed that it is the same sensor as the MAP sensor as previously mentioned.

I came across this on Amazon [https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 - Car MAP Sensor Vehicle Intake Manifold Air Pressure Sensor for 128i 325i 328i 330i E90 E91 E92 E82] $17.99 - 1 day Prime shipping. Just installed and worked like a charm. such a pain to install.. I did lose 1 of the torxscrews that was holding the sensor down... Anyone else lose 1? How deep is that hole?

[ErvinD]

Hi everyone. My E92 M3 has same problem. It is last the version from 2013 and only 73T km.

I drive it to BMW and they find 27E4 code.

Replaced the vacuum pump，checked the complete pipeline, checked the fuse, eventually，the problem is from the senser.

Just got call from BMW my car has been repaired.

[Nazty Naze One!]

Originally Posted by Datka

This thread will help many of us to avoid this problem in the future while doing the brake job.
I knew that we should be careful not to spill the brake fluid, because it can cause damage to the car paint, but wasn't aware of possibility to short that vacuum sensor which seems to be a big PITA to replace.

this! i swapped on some c63 amg brakes and figured yea just a bit of fluid was flowing from the top of the resevoir...it was a bit then i would've liked. after a long drive through some canyons, i came home parked it and the following day took her out and my car went into limp mode. a code popped up reading, 00279E. this shows an error with "oil condition sensor".

the swap took a bit of finessing with some magnetic tools and a solid headlamp but its totally possible. price of sensor $25.

[Redd]

Originally Posted by Adi123

It's a 15 $ fix! Got the sensor out very easily. Remove the torxscrews on the sensor, unbolt the ABS and make some space. Pull the sensorcable and you got it in your hands!

I checked the numbers on my pressure sensor and found a MAP sensor from a Z4 with the exact same number on eBay for 15$ (besides the production date). Immediately I heard that the pump stoped working overtime. Have been driving it for 3 days now, no codes, no limpmode

Any new feedback? Did this Z4 MAP sensor permanently fix the brake vacuum sensor problem?