2003 Astra 1.8 oxygen sensor fault

Discussion in 'Astra' started by brockbenson, Jul 30, 2020.

  1. brockbenson

    brockbenson

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    Hi All,
    I have a Astra G 1.8 and have been getting a random check engine light coming on. Put the scanner on it and got P0140 O2 SENSOR CIRCUIT NO ACTIVITY - DETECTED BANK 1 SENSOR 2. I assumed sensor #1 is the one before the cat and sensor #2 is the one further back under the car?
    The odd thing is that when I checked the live data sensor #1 was showing odd numbers, jumping between 0.135mV then 0.800mV then 0.095mV. Whereas sensor #2 was showing anywhere between 0.410mV to 0.425mV on the 10 minute test drive. Why would I get a fault code on sensor #2 when its reading seems in spec and no fault code for sensor #1 which seems well out of spec?
    Could anyone provide some help with this before I spend money on a replacement O2 sensor.
    Thanks, BB
     
    brockbenson, Jul 30, 2020
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  2. brockbenson

    brockbenson

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    Checked sensor #1 again and it was working fine. Sensor #2 would read okay for a bit then drop to zero and then return to normal (.410-.425mV). Replaced with a new NGK O2 sensor. After a few day driving the same fault returns. Any ideas, this is very frustrating. Thx
     
    brockbenson, Sep 11, 2020
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