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Discussion Starter #1
hi guys, please help

I am in California, just bought a used 2010 BMW x5 with about 95,000 miles on it. I was being cautious, and asked previous owner to provide a smog test, which she did. so we made the deal, paid her, drove home.

next day, 2 codes showed up on my Acron CP9580 scanner: P0420 & P0430

closer observation:

1. the cat temp11 an cat temp 12 is always about the same temperature, Cat11 is about 20 degrees higher than Cat12.
2. The O2S11 voltage and O2S12 voltage is also about the same.

Question:

1. is this an Oxygen Sensor(s) problem?
2. how many converters does this car have, do I have a bad catalytic converter, or two?
3. what other testings can I do with this scanner to pin point the problem?


Thanks so much!
 

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No ppi? No read the codes? no check for when the OBD was last reset?

What motor in that there X5?

Virtually impossible to fix this with only a generic OBD scanner.... not gonna scan your way to a diagnosis. IMO

Bad cats are actually very rare. More likle is a air leak or other issue leading to very rich conditions overwhelming the cats and confusing the O2s, resulting in cat codes.

WHat are your long and short term fuel trim numbers?
 

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Oh, if you go buy a new CAT, do not be surprised if you have the same issue in another 2k miles.....
 

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Discussion Starter #4
I have this Acron CP9580 scanner, still learning it, but if there are anything I should pay attention to, please let me know.

The scanner says sensors and cats are "OK".

I drove over 100 miles yesterday, and trip monitor still shows sensors and cats status as "incomplete".
 

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I have this Acron CP9580 scanner, still learning it, but if there are anything I should pay attention to, please let me know.

The scanner says sensors and cats are "OK".

I drove over 100 miles yesterday, and trip monitor still shows sensors and cats status as "incomplete".


Ok, WHAT engine?


Sent from my iPhone using Tapatalk
 

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Discussion Starter #8 (Edited)
hi guys, can someone please help me decipher these codes, and tell me WHAT needs to be tested/replaced:

at idle:

CAT Temp11: 802
CAT Temp21: 795
Long Term Fuel Trim 1: 5.5
Long Term Fuel Trim 2: 7.8
Short Term Fuel Trim 1: -0.8
Short Term Fuel Trim 2: -0.8
O2S12(V): 0.705
O2S21(V): 0.685

at 30mph:

CAT Temp11: 1131
CAT Temp21: 1140
Long Term Fuel Trim 1: -0.8
Long Term Fuel Trim 2: 0.0
Short Term Fuel Trim 1: -3.9
Short Term Fuel Trim 2: -2.3
O2S12(V): 0.690
O2S21(V): 0.470
 

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Seems like this takes more skills than the typical shade tree mechanic has. Lots of data and info in this thread, but no resolution that I can see.
https://www.bimmerfest.com/forums/showthread.php?t=1158473

You pulled the codes after you bought the car, but is there a check engine light or are the codes preventing you from getting the car registered? Trying to gauge you're trying to accomplish and I can;t tell if you're in a bind trying to jump through the DMV hoops or you found codes and trying to make sense of them / fix something. Did you clear the codes and they came back?

I'm so confused...
 

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....., and tell me WHAT needs to be tested/replaced:
Rarely works like that, for this issue.....

Spend your time reading and learning from the link that Fredo posted.

try to to guess at parts and replace them.
 

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Discussion Starter #11
ok. I was hoping someone can just tell me what's need to be done.

those 2 codes are "permanent" and I need to clear them.
 

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ok. I was hoping someone can just tell me what's need to be done.
Probably not for this issue- it isnt a 'heres the code, heres the part' type issue

those 2 codes are "permanent" and I need to clear them.
Can you delete them/clear them??? If you clear, it should clear- but then after some driving the codes may come back.

Does it do that?
 

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Discussion Starter #13
for car made after 2010, there are some emission relate codes can not be "cleared" (hence permanent) unless the issues have been addressed.
 

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No, you need to access it with INPA or other module specific code clearing. As I recall


I mean otherwise how would a 'real mechanic' be able to work on a car, then return it to the customer with the code cleared and light off? The car cant instantly 'know' it was fixed...and a mechanic cant drive it for a few hours....
 
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