Q7 o2 sensor replacement - B1 Sens 1

[ROOK13pdx]

08753 code, bank 1 sensor 1 out. I changed it without dropping engine or pulling the head









Pull far right sensor connection. Cut line. Plenty of penetrating oil, small handle tools and bloody little scratches.


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[titua1915]

hey. why did you switch that sensor? what error did it show on vcds? can you upload the log? i am having errors related to my cat. also what symptoms were you experiencing? any start up problems or anything?

[ROOK13pdx]

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[ROOK13pdx]

Now that this is fixed, having multiple misfires at WOT, come to find I have a good leak in a valve cover, getting into plug/coil pack. Can't win with this thing.


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[titua1915]

Now that this is fixed, having multiple misfires at WOT, come to find I have a good leak in a valve cover, getting into plug/coil pack. Can't win with this thing.


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What do you mean by WOT?


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[ROOK13pdx]

Wide Open Throttle. The O2 and the misfire aren't related.


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[flat12]

Nice job changing out that O2 sensor. I need to change one on mine, passenger's side after-cat sensor.....can hardly see it....let alone physically reach it. I'm getting a "cat efficiency" issue and am hoping that changing this sensor will fix it. Now I just have to get the nerve up to remove a bunch of things to get to it.

[ROOK13pdx]

cat efficiency is more likely your cat converters, unfortunately. In my experience, the efficiency code is the converter and the circuit error is usually the O2 sensor...


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[flat12]

Thanks for your input ROOK13pdx....I hope it's not the catalytic converter - I'm not sure I could even do that job. As noted above, I had the driver's side High Pressure Fuel Pump changed out a while back, and that cured a bunch of issues. I've been thinking I should change out the passenger's side High Pressure Fuel Pump as a preventive measure, as occasionally I'm getting a slight-rough idle, low idle rpm at cold start up, etc.

[flat12]

UPDATE - I managed to change out the passenger's side O2 Sensor aft of the cat - no more check engine light...! Yay...!

[titua1915]

hooray, @flat12. did you change it with aftermarket or oem? am thinking of using o2 mini cat spacers for both after cat sensors. i will replace some injectors to fix misfiring issues if that cures the misfires and only leave me with cat codes then i will try the spacers.

[flat12]

Sorry so slow to reply...I used a Bosch universal O2 Sensor and attached the OEM electrical connector. I also used a small spacer to back the O2 Sensor out of the exhaust stream, hoping that would eliminate the issue. However....after a few days, the CEL came back on. So ROOK13pdx is correct, inefficiency issues NOT the sensor itself. As you mentioned in another thread, you are looking at using a sensor spacer with a 90 degree elbow....I hope that works out.