Code p0431

2003 VOLKSWAGEN PASSAT
179,000 MILES
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IFYUSER
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I have the car listed above with a 2.8 liter engine. Code p0431 the guy said the pid for downstream sensor was fluctuating and that it should be steady. so he reversed the harness connectors between bank 2 and 1 and the pid was fluctuating in bank 1. so he knows it is not the catalytic converter. we had already changed both downstream sensors so we know it is not that. the only thing he found was that a pin for the bank 2 downstream sensor harness was broken he went to the junk yard and cut a pigtail harness to add to the old broken one. did he do something wrong connecting the splicing the harness. we know it is not the catalytic converter or downstream o2 sensors.
Jun 19, 2019 at 11:30 PM
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SCGRANTURISMO
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Hello,

This Direct Trouble Code (DTC) P0431 is for the warm up efficiency of the catalytic converter for bank 2 of your vehicle. The catalytic converter, through normal wear and tear is not operating as it should. In the diagrams down below I have included a factory troubleshooting guide for DTC P0431. Please go through this guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros
Jun 20, 2019 at 1:29 AM
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STEVE W.
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Swapping the sensors to test isn't a problem. However, it sounds like you have a problem with both sides and only bank 2 has shown a code so far.
Jun 20, 2019 at 5:23 AM
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