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      01-04-2014, 01:02 PM   #14
BMWM.D.
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Quote:
Originally Posted by Ingeniator View Post
Narrow band O2's are used pre cats to measure stoic/lambda the ECM then compares that signal with the reading from post cat sensors and it determines the Cat efficiency and flags if it does not meet emissions compliance.
Maybe this was just a typo..... but the N54 uses wideband pre-cat (control) oxygen sensors. The post-cat sensors are regular narrow band 02 sensors.
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