Virgin Member here. Question on bad MPG
 

HELLO BOYZ N GIRLS ! Wanna say that this site is great and have been surfin it since I bought my x5 2months ago and has helped me learn a lot about my truck. It's a bit of a learning curve coming from a life of Acura's to my first BM. I love my new baby but the gas is killing me at the moment??

So I picked up an x5 2006 3ltr- 2months ago with 104000km
Baby runs great except for bad gas mileage. im getting 23L/ 100km or for you U.S.A boyz thats 10mpg !? Yes most of my drivin is city/rural but it shouldnt be this bad?? :dunno: Changed MAF sensor and secondary and have a recent code p0141 - o2 sensor heater circuit bank 1 sensor 2? I've read here that a PRE cat sensor can have this issue with bad MPG but not a post o2 sensor?(unless I read wrong)? What else could be my problem? No rough idle, no misfiring, no hesitation...etc.. But...fYI I haven't done the 100k maintenance yet. cause...well I just spent 15k and its killing me to think that I have to put MORE money into it :((((

P.s I just tried tO post a pic of my truck from my IPad but website says picture too big?? I guess I'll try later from my computer cause ill have to resize the pic.

Glad to finally register and say hello ( as I was feeling like a spy just reading all the posts) loll
thanks to all and anyone that replies. Have a great weekend.

Welcome!!!

10mpg is not good. You are correct the pre cat 02 sensors are part of the system to control lean/rich condition. I am not that well versed on codes but as you probably know a code may be a part of the symptom rather than identifying the cause.

Were you able to find out any history of your X? Some of the 100,000mi. Maint. have been done earlier.

Welcome follow Canadian! Where abouts do you call home? I've got the same 3.0l in mine but I'm averaging about 12 - 14 l/100km mixed city and highway. I'm not sure what would cause your fuel usage, maybe the fuel filter? I've heard the Xs can be sensitive to dirty ones...good luck finding the cure:thumbup:

Welcome aboard!!

@bcredliner: The op's mileage of 104000k km is about 60k MILES for those south of the border. :)

To the OP, I don't mean to scare you...but these things aren't cheap to maintain if you want it to be reliable. Definitely NOT for those who just expect to put gas in and go.

Bank 1 sensor 2 is downstream sensor....after the cat. IIRC It basically serves to just monitor the state (efficiency) of the cat to make sure it is in fact functioning where as the upstream sensors ones also control a/f mix; as per bcredliner stated.

May sound trivial, but whats the air filter look like? What fuel are you using?

[QUOTE=bcredliner;947494]Welcome!!!

10mpg is not good. You are correct the pre cat 02 sensors are part of the system to control lean/rich condition. I am not that well versed on codes but as you probably know a code may be a part of the symptom rather than identifying the cause.

Were you able to find out any history of your X? Some of the 100,000mi. Maint. have been done earlier.

Thanks for your response,
I'm only the 2nd owner of my X and its KM not miles.. over all, service history was very minimal, never any big issues, even small ones were next to none. The guy who sold it to me only did like 10k in the last two years.( his wife normally drove it) She's a1 but I just find she's bleeding the bank with the gas issue.( The truck that is, not his wife ! ;) Maybe it's because I drive like I've driven all my 4cyl cars in the past. (A little heavy footed)lol.. regardless, I do have the po141 code but do I really need to change that o2 sensor for performance??

Don't know what to check? Maybe vacuum leak? Will have to bring it to someone I assume to get a proper diagnostic done as I'm not a mechanic per say..I can figure most general stuff, but no garage/ lift or time really. i guess I was just hoping for a magical 123 answer!

Thanks, glad to be aboard ! Ya I've realized fast that these things aren't cheap to maintain. Sounded like a great idea when I got it, but am slightly scared of anything major to happen. But she's so nice :)
Air filter is clean as I replaced her too and fuel I've been using 93octane (super in Canada) I mix it up sometimes with I think 91octane (extra) cause that stuff is becoming like black gold in the world $1.53 a litre which is like 6$ & something a gallon !! Crazy

Hey thanks, I'm out in Montreal Canada. Will check into the fuel filter. I'm thinking I gotta bring it to my mechanic for a once over cause I still haven't done it since I bought her cause she's been good other than the gas.

Why not try driving with a light foot on the throttle for one tank, and see if you notice a difference in the fuel economy? I never got worse than 14 l/100 km on my 2003 3.0, and that was in purely stop and go city driving. Better than that in mixed or highway driving.

Welcome.

Have you checked out either of the OBD II Code websites linked below, yet? If not, here's direct links to the P0141 code description...hopefully you'll find the description, symptoms, causes, and possible solutions illuminating:

1. P0141 BMW O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 2 OBDII Engine Light Trouble Code | Engine-Codes.com
2. OBD-II Trouble Code: P0141 Oxygen O2 Sensor Heater Circuit Malfunction (Bank1, Sensor2)

20 L / km is too high but you don't tell how you achieve this for the 400 to 500 km you're driving on the tank. All city, with 2 to 3 km trips where the engine doesn't warm up or a good highway stretch.

Regardless, as you have a clean air filter - the issue is quite likely related to engine management and the codes you see. Change your various 02 sensors (use Bosch) as well as your fuel filter (cheap prevention). Do you know how old your spark plugs might be? Change them ....

Then consider proactive (not so much even with the km you have) changing of transfer case, transmission and both diff fluids. Won't make a L / km difference but it will make the critical components last longer.