[CarEnthused]

I've done some researching on the Low Pressure Fuel Sensor after I got a few shadow codes indicating that mine was fried and I'm just trying to get some clear, direct answers on what exactly this means as far as how my car is currently running:

1st. As far as I know (I've owned my car for six months), this has been an issue the duration of my ownership, or nearly. About 3 months ago I started chasing some random misfires. Could this be related? They were only at idle. My plugs were near their expiration so I decided to just replace those. It didn't 100% resolve my issue.

2nd. I've heard that it's not a great idea to keep running with a bad sensor but it's not a deathly thing to do either. If I can I might fix mine, next month or later this month unless it needs to be done NOW. Can anyone elaborate on the risk, or lack of risk in running my car with the bad sensor?

3rd. Does this have an effect on gas mileage? I would imagine that a fuel-related sensor if failing or having failed might run the car rich (as opposed to risking a problem due to running too lean). Is this true? I've compared my numbers to other members gas mileage numbers and I haven't been too impressed with my own. I'm not sure if this is completely my heavy foot or if it's in any way related to the LPFS.

4th. If I decide I don't want to pay my dealer to replace this (It's not terribly expensive), and I want to do it myself, I've read that I need to take off the intake manifold. So I'm guessing that I would want to replace the intake manifold gaskets as well. Are there any other shadow costs that I might run into (gaskets, various parts that go bad in that vicinity) that I should take care of at the same time? If I do it myself I want to have all of my parts in the garage or on order so I don't have to DD my e36 m3 (she's great, but she's more of a toy than a DD at this point).

I'm trying to ask questions that I haven't seen answers too, or that I haven't seen completely answered. Hopefully this is helpful to more than just myself and future n54 owners will find this useful too

[INR96]

Stock I never had problem with the LP sensor. With a stage 1 tune and e85 tune, I noticed a problem between 2nd and 3rd gear when I felt like the engine would bog at half throttle. Eventually with e85 the engine started misfiring badly. I didn't realize that this was due to the engine running lean until I turned on the in dash AFR gauge. Changing the LP sensor seems to have fixed these problems for the time being. Maybe my LP pump is aging. I'm also getting about 3 to 4 mpg more.

I took some pics of my LP sensor change: http://www.e90post.com/forums/showth...5#post13871985

[Bimmer305]

1- Could be.
2- Low risk.
3- Every time the engine is not running perfect, it affects gas mileage. So yes.

4- The sensor is like $60 I think. Not to difficult to replace. There is a DIY around.
No need to take off intake manifold if you slide down the evil junction box (it was easy to remove on mine). Take off intake filters, charge pipe, throttle body move junction box and you are there.

http://www.e90post.com/forums/showthread.php?t=763958

[caliguy562]

I can only answer #4. If you can remove everything required leading to the charge pipe, then it is a diy. I would not pay the dealer $400-$500 for labor alone to do this simple job. You do not need to remove the intake manifold. You will need to remove the throttle body and black junction box. Like the above poster, mine was very easy to remove. I was able to get a good grasp and just pulled on the thing. I paid a little less than $100 for the sensor with shipping. A bit much for what the part is, but I look at how much I saved in labor and I'm good.

[Ch3ss]

what shadow codes were you getting?