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Z4 E85 CAT Issue

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Mogster4/4 View Drop Down
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    Posted: 03 Jul 2020 at 4:27pm
First time on the Forum and would would greatly apprecoate some advice please. 

I purchased my 2009 Z4 2.0i (last of the 2008 E85 specials run-off) with 66k miles from a local dealer just before the Covid 19 lock-down. it has a full service history and new MOT. Being in the 'shielded' risk category I didn't manage to get out much and when I did, the engine management light come on. With the Dealer shut down, I bought a BMW coded scanner (FOXWELL), which advised the following engine management issues :

2A70 DME valvetronic plausibility - sporadic current fluctuations, 
2C46 DME Oxy (Lambda) sensor 2 (pre-CAT)
2F45 DWE : EW5 data line

There were other electrical irregularities, but the battery had run low, so in order to avoid low battery related signals, I cleared all the faults and ran it 60 more miles, until the warning light appeared again. so with a full battery I reconnected my scanner and it advised that :

 P1170 - post catalyst fuel trim system correction value above threshold'.

I researched possible causes and found it could be anything from a failed CAT, or sensors, to a cracked manifold.

By this time (300 miles and 2.5 months) the dealer was starting to answer emails and I managed (by persistence)  to get him to have the problem investigated. He reported that "The CAT had failed and needed replacement". After more persistence he has arranged for repairs to be undertaken next week at no cost to me. 

My concern is that research on line refers to my car having 2 CATs, but I can't get far enough under my car at home to check the exhaust arrangement and the dealer can't (or won) tell me which CAT (if there are 2) is being replaced, or who he is using to carry out the work. I also asked him to ask his mechanics whether the exhaust died due to injectors leaking, but he ignored that one to.

My questions are therefore :

Does my car have 2 CATs ?
Does anyone know where I can look to find a schematic of the 2.0i E85 exhaust ?
Do the error codes indicate another issue such as failed sensors ?
I would like to know what to check (apart from whether the warning light comes back on again), when I get my car back. ?
Can anyone recommend a reasonably knowledgeable garage in the North Somerset area ?

I'm used to looking after my 1988 Morgan 4/4, which thankfully does not have any of the Z4's complex  electronics, so am not up to speed (no pun intended) with modern electrics. 

Many thanks,



Mogster
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Doddsy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Doddsy Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 5:29pm
Hello Mogster and welcome to the Club,

First off keep this link handy https://www.realoem.com/bmw/enUS/select
And pop the last 7 digits of your vin number into the box that says serial number. This will bring up the parts catalogue for your Z4. In there you will see a section for exhaust. 

You're correct. Unfortunately the 2.0 N46 does suffer from exhaust problems in particular a cracked manifold.  Certain models came with catalytic converters on the manifolds and secondary cats after the down pipe in the middle section of the exhaust. Double check what yours lists on the above link.

I would personally just leave it with the dealer to sort and if any warning lights come back on after the work is carried out then get straight back onto them.




Edited by Doddsy - 03 Jul 2020 at 5:33pm
Now: Z4C 3.0si Sport Manual Silver Grey
Gone:
Z4 2.5si M-sport Titan Silver
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Mogster4/4 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mogster4/4 Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 5:37pm
That's very helpful - thanks. I will visit the site now. What I will need is I reliable knowledgeable BMW  mechanic to check whether the work being done is satisfactory.
Thanks
Mogster
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Mogster4/4 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mogster4/4 Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 6:27pm
Hello Doddsy, just checked the exhaust section on the link you kindly provided, and unfortunately it appears to show two different manifold section options, which I am struggling to get my head around.

The first is titled "Exhaust manifold with Catalyst" but does not show any bulge for CATs in the pipework, which is confusing, and the second is titled "Lambda probe fixings" which shows two bulging CATs in the pipework, with the associated pre and post CAT probe locations. 

The "Front MUFFLER Section" is what I would call the mid-pipe section, and shows lambda probes either side of the MUFFLER, which presumably is a CAT (?). The tail section is shown without sensors with the tail-box which is just a silencer.

I'm confused as to whether my car has 1 CAT or 3 (?) and I can't get a view from above to see whether there are CATs in the Manifold section, and can't get the car onto my ramps to give me space to get underneath fr a look.

I'll buy better ramps and have a look after the work is carried out next week.

thanks again, 
Mogster
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