P0420 - passenger O2 below threshold .. interesting

[gaber6]

I already purchased a new downstream sensor for my v6 passenger side, but wonder about the error.

I'll reset the lights and they consistently come back on when I'm heading up a specific 40mph hill near my house and the engine lulls to 1k rpm and then downshifts. Really, no feel of strain, just consistent. It does come back on sometimes in random straight smooth drives as well.

I'll update this when the sensor goes in hopefully tomorrow to see if it stays out.

 

[gaber6]

Makes sense now.. went under the car and as soon as I tried to loosen the sensor, the exhaust shifted a tad. I reused the donut gasket when I did my head gaskets so I'm off to get a new exhaust seal.

 

[gaber6]

I finally put in the new sensor and donut and all is well.