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Discussion Starter #1 (Edited)
I'm having a rough time figuring out how to get my O2 readiness to set on my 2006 M5 with a Bren tune. When I emailed Bren they said "there is no way to shut them off. We have 100+ cars running this same file without issue/problem". I've driven the car for 3 weeks/2,000 miles under a wide variety of conditions and can't get the O2 to set. This is a problem because I have the primary cats deleted but need 7 of 8 readiness codes to pass inspection so O2 readiness is mandatory. I've been driving on a rejected sticker and only have a few weeks left to get this resolved.

The car is running great otherwise with no codes so I'm at a loss to what the problem is. I have been monitoring the O2 sensors and they seem fine although one runs about 0.05 volts higher than the other at idle (0.080/0.130).

Any advice is appreciated!
 

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Have you tried switching back to stock map to see if it's the tune issue? I have Bren Tune also, I actually just reset adaptations, so I'll check if mine go "ready".
 

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Discussion Starter #5
Unfortunately, I just had the tune installed instead of buying the handheld but even if I had the handheld, I think that would set a CEL for the cat delete so I'd still be out of luck!
 

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Discussion Starter #7
My understanding is these cars will throw a CEL (Check Engine Light) with the primary cat delete but maybe that isn't the case? I can source a stock DME from Jim Colley at Fast Attack if I were sure that would solve my problem?

I've already replaced a throttle actuator earlier this month along with some other repairs in May so I'm trying not to invest in a solution unless I'm sure it will work!
 

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My understanding is these cars will throw a CEL (Check Engine Light) with the primary cat delete but maybe that isn't the case? I can source a stock DME from Jim Colley at Fast Attack if I were sure that would solve my problem?

I've already replaced a throttle actuator earlier this month along with some other repairs in May so I'm trying not to invest in a solution unless I'm sure it will work!
I have primary and secondary deleted, no CELs.
 

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Discussion Starter #9
It sounds like picking up a DME from Jim Colley would be my best option if that is the case.

Thanks for the input!
 

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As far as I recall you will not get the readiness with primary cats delete. Even a new DME will not solve your problem. This is why the RPI headers were so popular, because they allowed owners to bolt on the primary cats again using the flanges.

A primary cat delete should give a CEL. It might take some time to pop up on some cars, but it will pop up sooner or later.

The only way to avoid the CEL is to cancel the cat efficiency monitoring, which is what the tuners do.
 

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As far as I recall you will not get the readiness with primary cats delete. Even a new DME will not solve your problem. This is why the RPI headers were so popular, because they allowed owners to bolt on the primary cats again using the flanges.

A primary cat delete should give a CEL. It might take some time to pop up on some cars, but it will pop up sooner or later.

The only way to avoid the CEL is to cancel the cat efficiency monitoring, which is what the tuners do.
That is my understanding also. I just had mine tuned out or the CEL would pop up after a few miles of driving.
 

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Discussion Starter #12
That is what I thought as well but Bren had told me that the readiness code should set which didn't make sense to me.

Looks like I have to put it back to stock to get this resolved. Header swap doesn't sound like a fun job!
 

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Perhaps your O2 sensor is showing not ready because it is not, it is actually defective?????


Flash the car back to the stock file and diagnose with BMW codes.


The DME will store a code for loss of cat efficiency. The SES light will come on. This should be overridden by any aftermarket header tune. No cars running the tune would pass OBD testing otherwise.


If you replace the DME, the light will go off. When the condition recurs because the cats are NOT THERE, the light will come on again.
 

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Discussion Starter #14
I haven't ruled out the O2 sensors but the voltages seem fine from the ODB2 monitor. I may go ahead and replace them anyway but I'm trying to narrow it down first! ; )
 

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A new DME will not fix the problem as already mentioned. You will just be creating more problems and have to program them out.

If it was me I would replace the O2 sensors and reset the DME. If that fails then it is something to do with the tune and contact Bren.
 

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Discussion Starter #17
No CEL and car is running great. Just can't get O2 readiness to set.
Thanks for the input from all. I've got a couple of things to try now.
 

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As mentioned, From what i know once you are catless, no tune or dme swap will set it to ready... A tune will switch off the CEL associated with being catless but will not be able to set you to ready for inspection.. States like NY, allow 1 not ready monitor to not be set and still pass inspection, for cars newer then 2001.. Good luck
 

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On the E60 M5 platform in order to get the CEL related to the exhaust you must delete the primary cats which have o2 sensors, one before the primary cat and one after the primary cat - both are a part of the headers. You can remove entire exhaust after pimary cats and CEL will never come on. Also, if you have a "stage 3" tune which is catless tune, you will have no CEL and will pass emissions with ease. I suggest tuning back to stock, wait for CEL to show up and tuning back to bc tune. Hope this blows away the confusion and helps set the o2 to ready.
 
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