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O2 sensor replacement

Discussion in 'E46 (1999-2006)' started by Touring525i4dawgs, Jun 30, 2018.

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    Touring525i4dawgs '02 525it M sport

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    I am coming up on my 100K service for our E46 and 200K for our E39 touring both 2002's. My
    mechanic could not find a service/replace/check list for 200K mileage. Both 100K and 150K service intervals require an O2 sensor replacement. Is this a good idea or replace when needed item? Is there a service interval checklist for 200K?
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    MGarrison

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    Hrrm... I don't know if there is specifically, maybe Charlson? I would assume it's the same as the 100k one. I _think_ a dead 02 isn't going to mean your dead in the water with either car if one happens to give up the ghost - I'd think most likely it'll throw a check engine light, and if the brain doesn't have 02 readings to go off of for your fuel injectors & fueling, the default fuel maps probably would go running rich and you'll start losing gas mpg's. I guess it depends whether you want to throw pre-emptive money at it or just see how long it lasts (assuming Charlson doesn't tell us I'm dead wrong lol :D)
    • Member

    Touring525i4dawgs '02 525it M sport

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    Thanks. We shall wait and see for Charlson's advice.
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    • Technical Service Advisor

    charlson89

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    BMW recommends O2 replacement in non CBS vehicle at 120K. I would say every 120k replace the o2 sensors is a good amount. Of course if you having a issue with the o2 sensors replace them even if the mileage is not reached. Normally the heater circuit on the o2 sensors fail before the actual oxygen sensor portion. When they fail if the heater circuit fails you will see a check engine light and the vehicle will run normal with no issues. If the oxygen sensor portion fails you can have running issues and it may not set a check engine light. I have seen vehicles buck and randomly die without ever setting a check engine light and it was a o2 sensor causing the problem. This of course the running issues is only for the precat o2 sensors. After cat do not really affect fuel function and just monitor how the cat is doing for emissions clean up.

    Garrison nice tech write up! :)
    Touring525i4dawgs likes this.
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    Touring525i4dawgs '02 525it M sport

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    Thanks for the info. Could this be the source of my intermittent check engine soon light?
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    • Technical Service Advisor

    charlson89

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    Hard to say would need fault codes to know if the o2's could be causing the possible issues.
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    Touring525i4dawgs '02 525it M sport

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    Will an OBD 2 pick that up?
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    frito

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    Yep, I have and OBD2 dongle and use Torque App on my phone. Picks up fuel trims, error codes etc. Also lets you clear certain error codes.
    Touring525i4dawgs likes this.
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    Touring525i4dawgs '02 525it M sport

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