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I originally posted in someone else's thread that had very similar problems... Thought I would share the resolution of the problem.
Sometimes the obvious, simple solution is correct.
I had replaced both front O2 sensors (Bosch 15175) and a day & a half later, the MIL came on again. When I finally looked at the new B1 S1 O2 sensor with VC-scope is was blatantly obvious, as it was flat lined... Turns out I got a bad sensor and coincidentally installed it where the old bad one was. I swapped it with an old, working O2 sensor and it was happy. So I exchanged the failed part for another new one and everything is OK now for over 5 days... no DTCs, no pending, all other diagnostic reports look good.
Below is a trace showing new, good sensors, power on, engine off, @ 0.450 V and then cold start, ramping up to normal oscillation...
Red: B1 Short Term Trim
Green: B2 Short Term Trim
YellowYellow: B1 S1 O2
LightBlue: B2 S1 O2
Full size trace image.
Sometimes the obvious, simple solution is correct.
I had replaced both front O2 sensors (Bosch 15175) and a day & a half later, the MIL came on again. When I finally looked at the new B1 S1 O2 sensor with VC-scope is was blatantly obvious, as it was flat lined... Turns out I got a bad sensor and coincidentally installed it where the old bad one was. I swapped it with an old, working O2 sensor and it was happy. So I exchanged the failed part for another new one and everything is OK now for over 5 days... no DTCs, no pending, all other diagnostic reports look good.
Below is a trace showing new, good sensors, power on, engine off, @ 0.450 V and then cold start, ramping up to normal oscillation...
Red: B1 Short Term Trim
Green: B2 Short Term Trim
YellowYellow: B1 S1 O2
LightBlue: B2 S1 O2
Full size trace image.
