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      08-22-2013, 04:33 PM   #1
///M Car Pusher

Drives: 2008 E92 M3 6MT
Join Date: Jul 2013
Location: East Coast

iTrader: (0)

DIY: Low Fuel Pressure Sensor Replacement

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!