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Discussion Starter #1
Diagnosing another issue I pulled codes: b3, Catalyst system efficiency, bank 2
No SES, never gotten that code before.

What does it mean and how do I go about diagnosing and repairing it (if necessary)?
I searched and got lots of posts in e63 forum for some reason. Related to the cats, or O2 sensors, or what else?

Thanks.
pablo-
 

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Diagnosing another issue I pulled codes: b3, Catalyst system efficiency, bank 2
No SES, never gotten that code before.

What does it mean and how do I go about diagnosing and repairing it (if necessary)?
I searched and got lots of posts in e63 forum for some reason. Related to the cats, or O2 sensors, or what else?

Thanks.
pablo-
Could be a variety of things, including bad cat (most unlikely), but the first thing I would do is check to make sure there are no leaks in the exhaust system. If you have access to a lift, it will be a lot easier.

The post cat O2 is seeing a reading outside its given parameters. So, after checking for leaks, possible replacement O2 post cat. How many miles on the O2's?

Regards,
Jerry
 

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when you reset the codes, does B3 come back?

How are your fuel trims? Vanos function? maintenance history?
 

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Discussion Starter #4
Could be a variety of things, including bad cat (most unlikely), but the first thing I would do is check to make sure there are no leaks in the exhaust system. If you have access to a lift, it will be a lot easier.

The post cat O2 is seeing a reading outside its given parameters. So, after checking for leaks, possible replacement O2 post cat. How many miles on the O2's?

Regards,
Jerry
No lift access but I'll put it up on jackstands and see if I can find evidence of leaks. I'm unaware of the O2 sensors ever having been replaced in the last 5 years (thats how long I had the car and the previous owner had car combined-I have previous maintenance history).
Car has 135k miles now. I bought it with 116k.
Thanks.


when you reset the codes, does B3 come back?

How are your fuel trims? Vanos function? maintenance history?
Havent reset it. Only just came up and I didnt clear it. I'll clear it and see if it comes back.
Fuel trims? Is that also on secret menu? I'll check if it is and report back.
Vanos don't sound bad at all so based on only that they seem fine. I dont know what symptoms would indicate they arent working well.
As long as I've had the car its been well maintained and I have the documented history of previous owner who only had the car 2 years. I've had it 2.5 years.
 

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No lift access but I'll put it up on jackstands and see if I can find evidence of leaks. I'm unaware of the O2 sensors ever having been replaced in the last 5 years (thats how long I had the car and the previous owner had car combined-I have previous maintenance history).
Car has 135k miles now. I bought it with 116k.
Thanks.



Havent reset it. Only just came up and I didnt clear it. I'll clear it and see if it comes back.
Fuel trims? Is that also on secret menu? I'll check if it is and report back.
Vanos don't sound bad at all so based on only that they seem fine. I dont know what symptoms would indicate they arent working well.
As long as I've had the car its been well maintained and I have the documented history of previous owner who only had the car 2 years. I've had it 2.5 years.
Generally any OBD computer or BMW computer can read fuel trims.

But really, FIRST thing is reset it and see what comes back. Could have been a 4 year old code. DO NOT bother with anything until you first determine you really have a CURRENT code.

You dont diagnose VANOS with sounds.... things like rich running is one of the symptoms, low power is another. But the sad truth is "good maintained cars" are rarely...and vanos begin to clog and fail over an extended period, until it gets to the point of causing issues. I am of the opinion that every E39M5 that has not have vanos maintenance yet, has vanos issues-perhaps sub acute, perhaps causing sluggishness or rich conditions, but no lights so owners just never know.
 

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I would not over think this code. Likely it is triggered by your other thread. The cool running is pushing it over the edge.
I concur with ard about vanos, likely that is what is getting the code close to the edge so cool running will trigger it.
Doing the vanos maintenance is a must.
 

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Discussion Starter #7 (Edited)
Generally any OBD computer or BMW computer can read fuel trims.

But really, FIRST thing is reset it and see what comes back. Could have been a 4 year old code. DO NOT bother with anything until you first determine you really have a CURRENT code.
I've read and cleared codes many times in the years I've had the car. This is a new code.
So with my Peake reader I can't read fuel trims? I don't have OBD/BMW computer. Is that something people with M5's typically have like a Peake reader?

I'll research VANOS maintenance and look through my paperwork from previous owner to see if its ever been done. I didn't know how to diagnose it and only know about the VANOS knocking/noise issue so thought that might be one way.

Thanks.
 
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