BMW M5 Forum and M6 Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
61 Posts
Discussion Starter #1
Hi Everyone, I just put my Peake code reader on my 2000 M5 and the code says B2 which has a description of "catalyst system efficency cyl 1-4. The code converts to hex 178. Does anyone know what this might mean. Is it a bad catalytic converter? Oxy Sensor? I've reset this code and it keeps comming back.
Thanks for any help.
Jason:M5launch:
 

·
Registered
Joined
·
445 Posts
what code table?

jpm5blu said:
Hi Everyone, I just put my Peake code reader on my 2000 M5 and the code says B2 which has a description of "catalyst system efficency cyl 1-4. The code converts to hex 178. Does anyone know what this might mean. Is it a bad catalytic converter? Oxy Sensor? I've reset this code and it keeps comming back.
Thanks for any help.
Jason:M5launch:
 

·
Registered
Joined
·
445 Posts
do you have an exhaust? if so, it's pretty common especially guys with tubi's and after talking to a lot of people there are a couple ways to fix it.

1) splice in an o2 simulator
2) powerchip software to increase the tolerance
3) reweld the last o2 sensor farther away from the cat.


If you don't have an exhaust, it usually is the cat.

hope that helps...


jpm5blu said:
I was using code table 18 in the peake research manual.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #5
I have Remus exhaust but stock resonators and pipes. Do you think the pre oxy sensors might need replacing? I have 56,000 miles. What is the recommended replacement periods for the oxy sensors. My gas mileage only averages 13-14 mpg lately for both city and frwy.:confused:
 

·
Registered
Joined
·
445 Posts
I was told that the precat 02 sensors and the post cat o2 sensors are only there for checking the cats. they say 95% of the time that you get catalytic ineffiencies are due to a cat going bad/clogged.



jpm5blu said:
I have Remus exhaust but stock resonators and pipes. Do you think the pre oxy sensors might need replacing? I have 56,000 miles. What is the recommended replacement periods for the oxy sensors. My gas mileage only averages 13-14 mpg lately for both city and frwy.:confused:
 

·
Registered
Joined
·
12,952 Posts
jpm5blu said:
Do you think the cats are covered under CPO warranty?
I think cats are covered under the emissions warranty, which is either 7/70 or 8/80, don't remember. As to pre cats, they in fact help run the engine properly closed loop. The post cat sensors merely compare the flow to precat, and can throw error codes as indicated above if the information it receives is outside a certain range.
Anyone getting 13-14 mpg on the highway needs to check precat O2 sensors at a minimum.
Regards,
Jerry
 

·
Registered
Joined
·
784 Posts
SANguru said:
I was told that the precat 02 sensors and the post cat o2 sensors are only there for checking the cats. they say 95% of the time that you get catalytic ineffiencies are due to a cat going bad/clogged.

The code here is related to the rear O2 sensor...... if the OEM cats are in place one or both may be giving up the ghost.....

FYI.... the front O2 sensors are required for engine operation........ they monitor and signal the DME to make fuel trim adjustments..... whereas the rear O2 sensors have NO affect on how the engine runs..... all they monitor is whether the cats are operating correctly....

First thing to do is swap the rear O2 sensors side to side, reset the codes and drive her.....if the problem follows the O2 sensor replace it..... if it remains with the same side.... likely a cat going bad.

I hope that this helps

Shadowman
 

·
Registered
Joined
·
445 Posts
good info.. I stand corrected..



shadowman said:
The code here is related to the rear O2 sensor...... if the OEM cats are in place one or both may be giving up the ghost.....

FYI.... the front O2 sensors are required for engine operation........ they monitor and signal the DME to make fuel trim adjustments..... whereas the rear O2 sensors have NO affect on how the engine runs..... all they monitor is whether the cats are operating correctly....

First thing to do is swap the rear O2 sensors side to side, reset the codes and drive her.....if the problem follows the O2 sensor replace it..... if it remains with the same side.... likely a cat going bad.

I hope that this helps

Shadowman
 

·
Registered
Joined
·
61 Posts
Discussion Starter #11
Thanks for all the useful info guys, This board is awsome with great people giving good advice. I will try swaping the rear sensors and see if the code switches to the other side.

Thanks again :cheers:
Jason
 

·
Registered
Joined
·
958 Posts
I posted that I had a 18-b3 code (so just 5-8 cylinder version of your code). I had stock exhaust. The dealer replaced the catalytic converter. This was done under warranty (the exhuast is warrantied for 80K miles). My car is a CPO 2000 MY M5.
 
1 - 12 of 12 Posts
Top