DIY: Low Fuel Pressure Sensor Replacement

[Infuzion]

So I've been romping around the forums here for a little while and finally decided to make an account and help out!

So my Engine kept throwing codes, such as High Fuel Pressure, O2 Sensors, etc. and had a really rough idle. BMW quoted me $1,600 to replace this. Essentially they were going to take the top of the motor off completely. While I would agree with them that this is a much easier way to actually maneuver this little sensor, I simply did not have the time to accomplish it, and I am deathly afraid of messing with these engines.

Tool list: (* = Optional)
-Beer (and cigarettes, if you smoke) - Mandatory. You'll want to shoot your E9X after this.
-Torx Wrenches - Lots of them, 20/30 were the common sizes.
-Socket Set - 10mm was the only one that we used, but a nice ratchet makes all the difference. You WILL benefit from many different angles of use from your extensions. Use wisely!
-Magnet* - When you drop something (assuming it's not uber-light aluminum) you want to get it. Getting parts for this thing is a whole new world of trouble.
-Vacuum* - Clean your air filter while you have it open, or replace it, but vacuuming out the seldom-seen parts of your engine is pretty sweet!
-Lint-free Rags (or microfibers)* - You may wish to stuff them in various places to keep debris out.


Long story short, I decided to do it in an afternoon with my dad while I was visiting him. There are 2 Fuel Pressure sensors. One is called the High Fuel Pressure Sensor, and is located directly behind the air-box. You can take the plastic stuff off and easily get to this thing.

The other (this one) is called the Low Fuel Pressure sensor, and is located behind cylinder #7 (driver's most-rear).

Start off by removing the air-box and air filter, along with the intake from the hood area. This should leave you with a giant hole into your "///M V8" cover.

Looks like this:

Random tip: the cover is actually 1 entire piece, not 2. DO NOT try jerking on it, you will not be able to get it off.

After the air-box covers and all are off, you can proceed to the ///M V8 cover. So start off by taking the 2 top bolts off (clearly visible). After that, you'll have to do some digging with a flashlight. Take out your 10mm (IIRC) and a long extension. The little boots that come down from the intake are actually holding the cover on. They need to be loosened...along with the camshaft vents (if that's the correct name).

To remove those little pesky vents, take the valve body cover dress off of the valve body cover (it's plastic with nothing holding it on, be careful!). You can loosen the camshaft vents and wiggle them around to ensure they're free. They will come up with the ///M V8 cover. Kind of a pain in the ass, but this is where you want to start using extreme caution. Remember that little plastic line you unplugged from the intake when you removed it? That thing barely moves. It's plastic, and will break as such. Be very careful when wiggling the top cover off, because breaking this means the air pump in your car no longer has a flow path. When you wiggle the cover off, you will notice a plug under the front of the cover. Remove this prior to pulling the cover off (self-explanatory).

Once you have the cover off, you'll notice that this is a pretty sweet motor . Here are all the parts that should be off of the car currently:

My dad is pointing at the sensor right here, and you can see now why it is such a pain in the ass:

Here you can see we loosened the air pump, and we started to loosen the wiring harness. It made all the world of a difference for us when we loosened the air pump. Although it's not 100% necessary, I highly recommend it:

Top-down picture of what space you're dealing with for this sensor:

This is the best possible view I could get of the sensor from inside of the motor. As you can see, it's a massive PITA! It takes a torx wrench along with a ratchet (that was the only thing that was small yet long enough to reach it for us!). I believe it's a 20 if I recall it correctly:

Bolt everything back up, clean up yourself and your car, have a beer, and take a picture of your baby ^-^:

If I missed anything or called anything by a mistaken name, I apologize, let me know and I'll fix it ASAP! My father is a mechanic and knows the proper terms, however I am not!

Thanks for your time, and thanks for being such a great community! Hope this helps someone out!

[elm3]

Great write up. Thanks for the DIY.

[nogo]

I saw your post and I viewed a few other posts and now I'm confused. I thought the low pressure sensor was right next to the air box hood intake hole. I need to replace my sensor and the fuel control module but I want to get the correct one. What was weird was that I took the part number off the existing sensor near the air box (PN 7547883-04) and I tried to find a replacement and it came up as an air conditioning sensor. I wonder if they are interchangeable or if someone installed the wrong part. My car has bucking issues when its cold and the idle fluctuates. It also pings at part throttle off idle which is annoying. The part I purchased is 13 53 7 614 317 so I hope it works.
Are you sure the sensor you replaced under the plenum wasn't something else? I'm an experienced mechanic but I'm new to working on the E90 M3.
There is a serious lack of helpful technical information on these cars.

[Bigraj]

~3 years later but I'm al little confused also. Specifically from this walkthrough:

http://www.m3post.com/forums/showthread.php?t=694148

Sounds like the same part in 2 different locations.

[Scharbag]

Originally Posted by Bigraj

~3 years later but I'm al little confused also. Specifically from this walkthrough:

http://www.m3post.com/forums/showthread.php?t=694148

Sounds like the same part in 2 different locations.

And 3 years after you were confused, I am lost. Does the S65 M3 have 2 separate low pressure fuel sensors?

[RoofusM3]

Originally Posted by Scharbag

And 3 years after you were confused, I am lost. Does the S65 M3 have 2 separate low pressure fuel sensors?

Currently doing my research to order this part. It sounds to me like there was an old low pressure sensor with a brass fitting used in 2008-2012 M3's that BMW discontinued. And that in those vehicles you have to order the new low pressure sensor and an adapter (part 16124800029).

You should be able to eyeball it. The lower pressure sensor is behind the air box opening that synchs with the hood vent. If you can see a brass colored sensor, probably need the part and the adapter.

[sixspeedm3]

Originally Posted by RoofusM3

Currently doing my research to order this part. It sounds to me like there was an old low pressure sensor with a brass fitting used in 2008-2012 M3's that BMW discontinued. And that in those vehicles you have to order the new low pressure sensor and an adapter (part 16124800029).

You should be able to eyeball it. The lower pressure sensor is behind the air box opening that synchs with the hood vent. If you can see a brass colored sensor, probably need the part and the adapter.

Here you go

[FormulaMMM]

Replaced the low fuel pressure sensor (as pictured just above) last week. had cel, rough idle, cold start, kind of choppy in gear revs here and there.

Can't remember the last time the engine ran this smoothly.. Now thinking the sensor was "fouling" long before the cel popped up, just slowly & progressively worse and I didn't notice.

For <$90 delivered from Turner, probably a good preventative swap @ ~50,000 mls. (I'm at 64k.)

[Pappas Fritas]

Originally Posted by RoofusM3

Currently doing my research to order this part. It sounds to me like there was an old low pressure sensor with a brass fitting used in 2008-2012 M3's that BMW discontinued. And that in those vehicles you have to order the new low pressure sensor and an adapter (part 16124800029).

Yep, I just did this update. I went with the FCP Euro Original Equipment kit (Part # KIT-13537622231KT) which is the following parts:
- OE Bosch Sensor (BOS-0261230348),
- BMW Adapter (BMW Part # 16124800029)
- BMW adapter O-Ring (13537559991)

FYI there is only one O-Ring needed, which is for the adapter threading into the fuel line. The newer style sensor does not require an O-Ring.

[kcdedric]

Just did my 2009 at 40k miles with the FCP kit (newer Bosch sensor). Since I already have the cowl removed using the BMS filters, I took off the driver side strut brace and was able to drop a deep socket right on the sensor without removing anything else. I really didn't want to remove the airbox/elbow because the Karbonius is kind of a pain to get back in place perfectly.

Car gave me the increased emissions light the other morning after a few miles of driving, so I pulled the codes and saw 27BA, 27BB, and 2B49. I also had a bit of a rough cold start before that particular drive but I figured it was just because the car had been sitting for a month. I have preventatively replaced the exhaust gaskets, all four o2 sensors, fuel injectors, and spark plugs in the past few thousand miles all before seeing any of these codes. Since it had only been a couple hundred miles since I replaced the fuel injectors I initially started thinking the codes were related to those, or maybe a bad coil. I decided to start with the fuel pressure sensor first being the one of the oldest and cheapest links in the equation. Sure enough, I took it for a drive today and no codes! Car pulled strong all the way to redline

[bugg]

Originally Posted by FormulaMMM

Replaced the low fuel pressure sensor (as pictured just above) last week. had cel, rough idle, cold start, kind of choppy in gear revs here and there.

Can't remember the last time the engine ran this smoothly.. Now thinking the sensor was "fouling" long before the cel popped up, just slowly & progressively worse and I didn't notice.

For <$90 delivered from Turner, probably a good preventative swap @ ~50,000 mls. (I'm at 64k.)

Seconding your experience here. Got an "increased emissions" warning that finally clued me into the LPFS. Replaced with the updated silver Bosch sensor and wow is it smooth now. I thought my rough idle was mostly due to resonance and my poly motor mounts, but it was mostly poor fueling. A bit of low-speed/rev bucking under light throttle is completely gone now.