O2 Sensor Issues

R

richardhei

Member
I am the proud new owner of a Z4 (2004). I have intermittently had the 'check engine' warning light illuminate. I have just bought an OBD II Diagnostic tool. It suggests the O2 Sensor has 'no activity'. This could be either the sensor itself, or the connection. I have done a little research (correct me if im wrong) the Z4 has both 2 'pre cat o2 sensors' and 2 'post cat o2 sensors'. How can I tell where the problem lies? It appears the 'pre cat' sensors arent too difficult to change. The post cat (im guessing) are accessed from beneath the car? I dont have access to jacks/car lifts so am I best to take it to the garage? (what prices should I expect). I am relatively happy to carry out the work myself, but not very experienced. Please give me some pointers...

Thanks
Richard
 
Plenty of info on 02 sensor issues use the search facility, welcome to the forum. Cheers Baz :thumbsup:
 
Pre cat pretty easy to change, post not so and without kit you're going to need to take it to a garage.

Pre cat are more likely to fail though so you may be in luck. If your OBD tool is basic and doesn't provide more info then you'll either have to buy a better one or take it to be diagnosed.
If it was me, I'd get an OBD-USB cable off eBay (£25 for mine) and delve in, you're going to pay at least that for someone else to do it. That will tell you which it is.
 
Thanks guys, it appears the sensor in question is Bank 2 Sensor 1.

I am reading that Bank 2 refers to cylinders 4-6 (which I believe is towards the rear side of the engine?). Sensor 1 refers to the 'pre cat' sensor (This was in a forum for a different BMW model, so may not be correct). Could anyone advise?

I'm looking for confirmation of which sensor I need to be changing? I haven't worked on my car before, but this task seems like a good place to start. (I did phone a garage for a quote anyway, they suggested I reset the error and see if it returns, as it may just be a one off). So I have done that for now.

I am tempted to try this fix myself regardless, it seems to me that the 'below link' is the sensor I want. I just want approval from someone who knows what he's doing before I go diving in.

http://www.ebay.co.uk/itm/Front-pre-CAT-Lambda-Oxygen-O2-Sensor-for-BMW-3-5-7-Z3-Z4-/331081632112?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4d1600c970

Thanks, any help appreciated.

Richard
 
Not long after i bought my zed i had a management/warning light come up, didn't seem to affect the performance at all, had it reset with a mates hand held diagnostic tool only for it to come back shortly after.

Mate diag tool wasn't clever enough to pinpoint the problem so i took it to Cooper BMW and they did a £50 diagnostic check, come back as a pre cat sensor fail and a huge bill to change it :o

I ordered a replacement £200 :o :o from BMW and fitted it myself, quite an easy job really but i struggled as i didn't have a Lambda socket, def def buy one of these, its like a spark plug socket with a slot in it for the cable on the sensor.

Oh and i had to have the warning light reset, been good ever since, have a go at changing it :thumbsup:
 
You need to read the codes as stated otherwise you will just end up stumbling around in the dark. A check engine light could also possible indicate that the Vanos solenoids require cleaning
 
If you are 100% sure of the location then you can sort it yourself. I was quoted about £225 to do the job - it's fiddly but certainly not worth that price! That eBay link does not look anything like mine but then I have an 06 N52. Get someone here to check your part choice, buy a lambda socket and DIY. There was a bracket covering mine (which I've since not replaced as only the wiring clipped onto it - it's not flapping about so just seems unnecessary) which needed some inverse torx to get off, had to get under to reach it and needed another pair of hands.
 
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