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Reply To: P0420 after changing parts

Adrian Ilinca
Adrian Ilinca

earlier today, noticed something strange. With the AC on, the o2 downstream sensor started to randomly switch from 0.7 to 0.1, 0.2. When turning the AC off, it stays steady around 0.7. I start to think that the car is possesed by some o2 sensor demon. Tomorrow I am going to clean all the grounds I can find in the engine bay, maybe there are some corroded or something and giving strange signals in the electrical system. While this switching appears, the engine runs perfectly fine, no hesitation, no rough idle, no nothing.