The P0300 Saga

Natrix · 01-01-2023, 11:16 PM

Thanks for the input!

I did check resistance across t3 and t4 on both upstream O2 sensors, and they were in spec. They also output the ”correct” voltage range at idle, at least according to one example I found. I also checked continuity from each one to the ECU and checked for short circuits. I think all is well with my O2 sensors.

I would definitely recommend checking yours based on your issue, though. If you’re seeing a code pop up directly related to a component, it seems likely to be causing the issue.

On the 350Z, I have seen a case where the O2 sensor wire was not routed correctly (it was not pushed into the factory clips), and had gotten too close to the exhaust and melted. That caused a MIL and an O2 sensor code.

I hope you solve your P0300 issue without too much difficulty.

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01-01-2023, 11:16 PM	#6 (permalink)
Natrix Base Member Join Date: Jun 2019 Location: SoCal Posts: 22 Drives: 40th Anniversary Rep Power: 6717	Thanks for the input! I did check resistance across t3 and t4 on both upstream O2 sensors, and they were in spec. They also output the ”correct” voltage range at idle, at least according to one example I found. I also checked continuity from each one to the ECU and checked for short circuits. I think all is well with my O2 sensors. I would definitely recommend checking yours based on your issue, though. If you’re seeing a code pop up directly related to a component, it seems likely to be causing the issue. On the 350Z, I have seen a case where the O2 sensor wire was not routed correctly (it was not pushed into the factory clips), and had gotten too close to the exhaust and melted. That caused a MIL and an O2 sensor code. I hope you solve your P0300 issue without too much difficulty.