O2 Sensors
 

Hello guys,

My 4.4i X5 has number of things to have replaced. Thermostat, 2 O2 sensors(One front on bank 1, and One rear on bank 2) and a Mass Air flow sensor. I have bought a New Thermostat and going to buy a new MAFS. as for O2 sensors, there is only one Dealership in my city/countrey. and they don't have them in stock. My mechanic told me that I can buy used one as far as it's good. I have found both of them for 60$ with the warranty that they are working. I need your advice... should I buy used once? or wait for them 2 weeks? and also if it is reccomended to change all them at a time.

Nick

Buy new ones. Here is a few sites that will help you:
BMW Parts and BMW Accessories | Bavarian Autosport
Pelican Parts - Porsche Parts & BMW Parts - Automotive Parts and Accessories - Porsche & BMW
OEM / Performance Parts for Audi, BMW, Mercedes Benz, Mini, Porsche & Volkswagen - ECS Tuning
Auto Parts at AutohausAZ - OEM Auto Parts - Discount Replacement Parts, Resources and Car Care Tips

and should I replace all four of them or should I just replace 2 that has fault? If I'ts not necessary then I would leave them for now, Because I have as I mensioned few more things to deal with. and I just finished fixing timings, ect.. so... Thanks

If you are on a budget replace the two that are bad. How old are the others? If they have 60-80,000 miles on them you may want to consider replacing them as preventative maintenance. Be sure to buy the O2 tool for removing them it makes changing the sensors a very simple job. It is possible to do it with out the tool but just more time consuming. Check the Article Section to see if there is a DIY.

First of all good job on that milage of yours.

The milage is 135k miles, As for maintenance I don't know because I got the car in auction and don't really know what's been replaced, but the car was in terrifle condition. Timings, Tranny, Air suspention bags, ABS module and many others that I had to fix. So I doubt that anything was ever replaced on this X except for Plugs, but the engine is in Prectine condition. I will get the other two sensors replaced soon as well.

Thanks for the tips,
After this I will have TC left, because It's making those tikking metal sounds when changing gears.

How did you get it at the auction? Do you know somebody with a dealer's license? Only reason I ask is that I would like to do the same in the near future.

Yeap, I do. but in NY. Cars are cheaper on auction, but they need maintanance work more. up to you to decide what suits you more.

So, I changed the Thermostat. the O2 sensors had errors no more. I refuled with bad fuel as an emergency, I guess that was the reason. then the new problem came up,
AirBag light... the computer guy told me that It's module from underneath the parking brake in central console... any ideas? could you guys post any diargrams?

RealOEM.com has most of the diagrams. If you need anything more detailed, it would probably be a good idea to pick up the Bentley manual.