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Old 03-07-2011, 07:02 PM   #5
El Polo
Registered User
Join Date: Feb 2010
Location: Canada
Posts: 461
My Ride: 99 black 328i
Starting to troubleshoot


Just scanned my OBD and got those 3 codes:
  • P1181 O2 Sensor Signal Circuit Slow Switching From Rich to Lean (Bank 2 Sensor 2)
  • P1183 O2 Sensor (Bank 2 Sensor 2) Open Circuit During Coast Down Fuel Cut-off
  • and P1397 Camshaft Position Sensor "B" Circuit (Bank 1)

For now I'll focus on the O2 sensors (CPS will be replaced).

I took a ride to log the activity of the 4 oxygen sensors, and here is an extract of 1 minute of city driving shown as a graph.

Few questions:
  1. Which one is the Bank 2 Sensor 2? pre or post-cat?
  2. I thought O2 sensors always fluctuated between 0.1V and 0.9V, but I see between 40 and 50 seconds on the graph that they went to 0.0V. Why? Should I worry?
  3. Should O2 sensors be replaced by pair?

Click image for larger version

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Thanks a lot!
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