improving gas mileage 101

1) replace air filter
2) replace spark plugs
3) replace fuel filter
4) use only 93 octane or higher fuel
5) change driving tactics
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good luck

Yes I've tried on many tanks of gas to drive like a granny and still my best tank of gas was 20L/100km. Most of my driving is like 10 km trips and its mostly rural stop and go almost no highway.

Ill take the advice given and start with the sparkplugs, o2sensors, gas filter and a full change of fluids see what that does. .

X5SND-The but after I don't mean to scare you means you do mean to scare him. IMO, we should stick to welcoming OP and providing input to help him correct the problem he is having rather than telling him he made a terrible mistake. None of us know the history of the vehicle so we don't have a clue how it was maintained or what preventative maintenance has already been done. I don't understand why one would want to be a part of the forum or own a X5 if they are all such a money pit.

Canadian-boy, I have had very few problems and am north of 108,00 miles. Stick to enjoying your new X. You might have some problems, you might not. You can deal with it if it ever happens.

It would help to know on a 1-10 how comfortable you are DIY. We don't know how you pulled the codes and quite often some of the codes are symptoms rather than causes. JCL has offered good advice, before throwing parts at it to see if one of those darts hits the bulls eye, see if you are enjoying your X a little to much with your right foot. If you are sure that is not the problem then we can provide you with a troublehooting sequence that will have you replacing as few parts as possible to fix it.

improving mileage 102
check for codes
troubleshoot code related causes in logical sequence
replace or repair one part
check mileage
repeat the above until problem is resolved

If you prefer you can start with--
Check air filter
check spark plug(s) replace all if checked plugs indicate
Replace fuel filter--easy and inexpensive
Check mileage and if code is still there

There may be a better sequence, It would be good if JCL provides his, but a good way to make a X expensive is to throw parts at it when you have a problem.

If you still have a P0141 OBD II code...see the links in post #9...both links list causes, symptoms, and possible solutions for that code.

It's ok x5SND didn't scare me or say anything I didn't already know. As far as DIY there's not a problem for me to do small things maybe to answer ur question 7-10 my capabilities. as long as i have instructions i can manage. I pulled the codes from a generic OBD2 wifi reader through my IPhone. I originally had a P1092, P1419 and the Po141 codes when I bought the truck. Through trial and error and reading the forums, I ended up replacing both Maf sensors and cleared the codes and now its just my P0141 keeps coming back. I've been browsing prices for the o2 sensors and Bosch are 75$/ea sounds right? Those seem super simple to change, pre-cat anyways, think I just need the special tool right? I will change spark plugs too? Haven't checked but that should be simple enough to do aswell? These are things that should be done at 110k anyways, so I might aswell. Any specific or recommended plugs I should buy? Thanks again for the help

For price comparisons I go to Furiousmethod.com - BMW Parts Price Comparison

Since the pre cat 02 sensors are part of the fuel management system I only buy OE or OEM parts. Some buy generic sensors but I just feel it is better not to add a potential, hard to confirm problem to the fuel management. I have always used the special tool that I rented from a chain auto store--not sure what is available there. The sensors are very easy to change unless they have been subjected to lots of corrosion. If that is the case a couple of rounds of penetrating oil and they should be good to go. The special tool is helpful for that situation.

I am extremely performance minded but didn't change plugs until 90,000 mi. Plugs usually let you know they are bad with stumbling at idle or an engine miss. It won't hurt if it gives you more peace of mind. As far as plugs--use OE plugs. They are plenty good and they last so long if they cost more it is not that much per mile.

Hey thanks for that link I appreciate it. I found the 02sensors through there at RockAuto parts for 52$ a piece. It's crazy my auto parts store here in Montreal 'napa autoparts' quoted me 132$ ea and for NGK brand? Any personal feedback on RockAuto Parts?

1 other question, when I've cleared my engine code of the P0141, it literally doesn't come back on till I've driven another 300km or more? Also I noticed that my oil change indicators have been showin 3 bars since I bought it and I know its like way over due to be changed? Is it possible when I've cleared the engine light it has been resetting everything else too? ( sorry if that's an amateur question) and thanks again for your help

SES/CEL/MIL reset is OBD II only and is a completely different system vs the SI lights & their reset procedure.

http://www.bimmerboard.com/members/q...Connection.jpg


The SI lights go off according to how much fuel your X has consumed. It's not a mileage based system. See the info below that explains the OIL SERV & INSPECTION lights (SIA III):

http://www.bimmerboard.com/members/q...0Explained.jpg

Very informative, thank you for that. The previous owner of my X5 did last oil change at 79059km and my X now has 109000k. I just thought maybe I had reset something by mistake because i kept thinking that It's definatley over due (30,000km) and couldn't understand why I still only had 3 bars showing on the service indicator??