DTCs P0300 and P0131

2003 PONTIAC MONTANA
87,500 MILES • 3.4L • V6 • 2WD • AUTOMATIC
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XJSHEN
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my car got P0131 pending, heated oxygen sensor (HO2S) circuit low Voltage bank1 sensor 1. P0300 pending, engine misfire detected.

I collected OBD monitor test result with scanner, but do not know how to explain the result. If these indicated EGR problem, EVPD leak, O2 sensor problem?

Here is result:
- Oxygen sensor monitors and constants $05

- Oxygen sensor heater system time to activity monitor $06

- Exhaust gas re-circulation system monitor $07

- Enhanced evaporative system monitor #2 (020” leak) EVPD $0A

- Catalyst efficiency monitor $0C

- O2 sensor heater system current feedback monitor $0E

Thanks for your instruction and helps!
Sep 4, 2020 at 5:05 PM
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KASEKENNY
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That data is just the internal module monitor. This is actually the hexadecimal code that the scan tool is suppose to decode for you but your tool is not capable of doing that. Most generic scan tools do not contain this ability. Unfortunately it does not aide in figuring this out in this form.

So I attached the testing that we need to do for the o2 sensor code. More then likely this is causing the P0300 so let's fix that one and retest for the others.

Let us know if you have questions on this info and we can go from there. Thanks
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Sep 4, 2020 at 7:40 PM
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XJSHEN
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Thanks! I do not know how to test oxygen sensor B1S1 and B1S2 on the DTC p0131. There are 4 legs on oxygen sensor B1S1 (upstream O2 sensor). Disconnect the wire connection and test voltage on the O2 sensor legs? There are two white wire, and one black and grey wire on the connection socket. How to test the voltage?
Thanks!
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Sep 6, 2020 at 12:09 PM
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KASEKENNY
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Do you have a scan tool that can monitor the o2 sensor voltage? If not, that will make it tougher. Basically we need to see what the PCM is seeing which is what a scan tool will show you.
Sep 6, 2020 at 5:43 PM