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I just replaced my rears yesterday. This guide was helpful but I would like to add 1 thing.

When pulling out the old rear ones, I tied a string to the end on the top side, so when I needed to route the new sensors wire back to the top, I just tied it to the string and pulled.
 

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nice DIY
I need to do this soon
 

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If I disconnect my pre-cat 02 sensors will this allow me to assess whether my power problems are due to a bad Cat? i.e. if my power problems are solved its the bad reading from the o2 sensors causing a poor air/fuel mix. Will disconnecting the pre-cat 02 sensors allow this?
 

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bumpin to remind myself to change these
I think i'll do the precats first then post when im not as lazy
 

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Great write up, very useful but one thing missing.

Error codes refer to bank 1 or bank 2. As I understand it, bank 1 is cylinders 1-3, bank 2 is cylinders 4-6.

Although when you get into the job you can probably work it out (am I right assuming cyl 1 is at the front and cyl 6 at the back ?), it would be really useful if the sensors and connectors in the pictures had been labelled as to which was the bank 1 or bank 2 post-cat sensor and plug. If I get a bank 1 error (P0420 - cat bank 1 below efficiency actually, but the car's passed an emission test in the MOT so I suspect post-cat sensor at fault, not cat) I'd like to know which sensor to look at (so I know in advance whether it's the "easy" one or the "hard" one I'm looking at changing).

Can anyone help with that info ?
 

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Vexed !!!

Cheapest price I can find for OEM (post-cat sensors) Bosch part number 0258005109 in UK is: Bosch Direct Fit - (wires 4, cable length 990mm) £71.68 inc VAT & UK deliv. (= $139.55 USD !!!)

That's $80 more, for the same OEM Bosch part that I've seen advertised in the US for $58-$60 !!! :mad:

http://www.lambdasensor.com/main/bosch/price.pl?item=0258005109

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1433864&parttype=5132&a=UKc1433864k279826

http://www.autohausaz.com/search/[email protected] System&[email protected] Sensor

Can anyone recommend a supplier who will supply at similar prices and ship to UK at a reasonable price ? I'm gonna have to check around the web further too I think.
 

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guys, my car is giving faults:

-AfterCat oxygen sensor short to B+, Cyl #4-6
Peake Research code: 15 9F...I keep getting this code

-AfterCat oxygen sensor disconnection, Cyl #4-6
Peake Research code: 15 D8...I only had this code once



So I am only going to replace the one post-cat O2 sensor, not both.
Is that OK? Or is there some reason I am unaware of that I should do both?

Also Im not sure which sensor is for cyl #1-3 and cyl #4-6. Does anyone know?

Any other advice is appreciated
Thanks for the help!!!!
 

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guys, my car is giving faults:

-AfterCat oxygen sensor short to B+, Cyl #4-6
Peake Research code: 15 9F...I keep getting this code

-AfterCat oxygen sensor disconnection, Cyl #4-6
Peake Research code: 15 D8...I only had this code once



So I am only going to replace the one post-cat O2 sensor, not both.
Is that OK? Or is there some reason I am unaware of that I should do both?

Also Im not sure which sensor is for cyl #1-3 and cyl #4-6. Does anyone know?

Any other advice is appreciated
Thanks for the help!!!!
Anyone?
Which POST CAT sensor is for cyl #4-6??
 

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Error codes refer to bank 1 or bank 2. As I understand it, bank 1 is cylinders 1-3, bank 2 is cylinders 4-6.

Although when you get into the job you can probably work it out (am I right assuming cyl 1 is at the front and cyl 6 at the back ?), it would be really useful if the sensors and connectors in the pictures had been labelled as to which was the bank 1 or bank 2 post-cat sensor and plug. If I get a bank 1 error (P0420 - cat bank 1 below efficiency actually, but the car's passed an emission test in the MOT so I suspect post-cat sensor at fault, not cat) I'd like to know which sensor to look at (so I know in advance whether it's the "easy" one or the "hard" one I'm looking at changing).

Can anyone help with that info ?
Anyone?
Which POST CAT sensor is for cyl #4-6??
Summer must be here, we had a warm day on Sunday so I got outside under the car and did an oil change.
While I was under there I thought I'd trace the exhaust pipes, finally take some pics and answer this question.

Both post-cat sensors are easy to reach but the Bank 2 sensor (cyl 4-6) will be more fiddly to undo, as the 22mm "sensor socket" (with a slot in it, picture attached) will have to be turned and repositioned just like with a normal spanner. Due to the wires you can't just undo it with a rachet. An open-ended 22mm spanner will be fine for Bank 1 (cyl 1-3) sensor (You couldn't use a "sensor socket" on this, there isn't enough clearance to get a rachet on it.).

(You won't have the advantage of being able to see the view in the 2nd picture. This was taken by holding a small camera in the gap up above the exhaust).

Photos include details of post-cat sensors, and the tools required to replace each:




 

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Great write up, very useful but one thing missing.

Error codes refer to bank 1 or bank 2. As I understand it, bank 1 is cylinders 1-3, bank 2 is cylinders 4-6.

Although when you get into the job you can probably work it out (am I right assuming cyl 1 is at the front and cyl 6 at the back ?), it would be really useful if the sensors and connectors in the pictures had been labelled as to which was the bank 1 or bank 2 post-cat sensor and plug. If I get a bank 1 error (P0420 - cat bank 1 below efficiency actually, but the car's passed an emission test in the MOT so I suspect post-cat sensor at fault, not cat) I'd like to know which sensor to look at (so I know in advance whether it's the "easy" one or the "hard" one I'm looking at changing).

Can anyone help with that info ?

Hey Tony, I have the exact same error on my 03 M3 saying htat efficiency for bank 1 is below threshold. Did you fix your problem and did the light go off? I was just wondering if you could help me out because I'd like to do it myself. Was it a post-cat sensor and did you just have to replace one? Any help would be appreciated. Thanks.
 
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