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  1. #1
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    Oct 2007
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    Default O2 sensor for my 2001 Focus SE

    I am a relative novice to auto maintenance but I need to have my O2 sensor's replaced and am going to do it myself (my mpg has been dipping over the past 1-2 years from around 26mpg city to currently 20mpg). I've located both the sensor on the manifold before the catalytic converter and the sensor after... do I need to replace both? As far as I know, neither have been replaced before and I'm creeping up on 90K miles. I'll also be cleaning my MAF sensor while I'm at it... any comments, tips or suggestions are welcomed.

    While I'm at it - what other tune up suggestions above and beyond the normal "oil change" and "tire rotation" routine should I be looking to do? I'm enjoying learning about my car and doing some work to it. Ive went from being hands off to changing oil, rotating tires, changing rotors & brake pads.... and now the sensors. I'd like to learn more please.

    Thanks!

  2. #2
    Super Moderators GapBoyPCS's Avatar
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    Oct 2001
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    Waterloo/Toronto, Ontario, Canada
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    Default Re: O2 sensor for my 2001 Focus SE

    Some of the advice will depend on what engine you have in your Focus.

    I'm not entirely sure why you need to have the O2 sensors replaced, aside from the drop in mileage. A lot of other things can impact mileage, like spark plugs, tire pressure, or air filter or maybe even the gas you're using.
    Richard
    2002 ZTS | Sangria Red |
    Over 521,000 km and 323,000 miles
    2012 SE Sport | Red Candy | Over 53,000 km and 33,000 miles

    [FJ] focaljet - Forum Guidelines - Welcome to the Jet - 2012 Focus - Team Canada - FJ Store - Sponsors - SEARCH

  3. #3
    TEAM Member JTs04SVT's Avatar
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    Default Re: O2 sensor for my 2001 Focus SE

    I was wondering how hard it is to change it too. Mine has gone out as well and I got under the car today, but can figure out how to get it off since the bracket connecting the manifold to the cat is blocking it. Any advice?

  4. #4
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    Jan 2010
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    Austin, TX
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    Default Re: O2 sensor for my 2001 Focus SE

    Ceighmey when did you change the fuel filter last? If it has been over a year or 20K miles I would start there. Next spark plugs and wires if they have not been changed yet. Motorcraft or Autolite plugs are preferred.
    02 ZX5

  5. #5
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    Oct 2007
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    Default Re: O2 sensor for my 2001 Focus SE

    I have a 2.0L DOHC engine inmy focus. Spark Plugs are less than 2yrs old, air filter replaced every 5000 miles with oil change, unleaded gasoline, good tires... nothing in the way I drive or maintain it has changed in the past 7-8 years since i bought it other than my MPG are dropping recently.

    When i read about O2 sensors on line there are alot of reccomendations that they be replaced every 30-40K miles. That may be overdoing it, but since I have 89k on mine and have never done it, is it so odd to think it would help?

  6. #6
    Super Moderators GapBoyPCS's Avatar
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    Default Re: O2 sensor for my 2001 Focus SE

    Maybe it's me, but 5,000 mile interval changes for the air filter seems a bit extreme unless you're in a really dusty environment. Ford's own maintenance pamphlets don't start to address air filter changes until every 15,000 miles or so, depending on your type of driving and you using a good quality brand of air filter.

    For a lot of posts on here regarding fuel economy, the cause(s) vary. There's no magic bullet that says "part X" or "sensor y" is the problem. You can try the O2 sensors, but if you don't have any engine codes or major issues that tie the O2 sensors to your problem it can be a gamble (so you could be throwing your money away). I think that's what deezx5 and I are implying.

    You're on the right track by finding out what kind of service you need. I'd first go to www.flmowner.com to see what kind of maintenance Ford suggests at 90,000 miles. Luckily, it's handy

    90,000 Mile Service Schedule


    • Change automatic transmission fluid
    • Replace fuel filter
    • Inspect automatic transmission fluid level (if equipped with underhood dipstick)
    • Replace cabin air filter
    • Replace engine air filter
    • Perform multi-point inspection
    • Inspect and lubricate all non-sealed steering linkage,ball joints,suspension joints,half and drive-shafts and u-joints
    • Inspect brake pads/shoes/rotors/drums, brake lines and hoses, and parking brake system
    • Inspect complete exhaust system and heat shields
    • Inspect engine cooling system and hoses
    • Change engine oil and replace oil filter
    • Rotate and inspect tires; check wheel end play and turning noise

    Richard
    2002 ZTS | Sangria Red |
    Over 521,000 km and 323,000 miles
    2012 SE Sport | Red Candy | Over 53,000 km and 33,000 miles

    [FJ] focaljet - Forum Guidelines - Welcome to the Jet - 2012 Focus - Team Canada - FJ Store - Sponsors - SEARCH

  7. #7
    TEAM Member
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    Austin, TX
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    Default Re: O2 sensor for my 2001 Focus SE

    I can see changing the air filter at 5K, here in TX I have to clean and oil my filters several times a year due to pollen season, dust season. Ford doesn't even recommend replacing the 02 sensors and when I pulled my cat last just after 100K to put on a shorty header both sensors looked brand new.

    Assuming your drop in fuel economy is not related to a winter blend gas I still suggest fuel filter. Its a lot cheaper than 02 sensors and pretty easy to do.
    02 ZX5


 

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