Hi everybody 👋

I have a 2004 XJ8 and recently replaced the upstream oxygen sensor bank one passenger side ( in USA) and drove the car for about 5-8 miles and the check engine light went away but it came back on 2 days later.

I have not idea why , I installed the OEM upstream Denso oxygen sensor also since the car is about 16 years old I decided to install the driver side upstream o2 too as well even when it was not bad. Only the passenger side, bank one keep saying P1646. I checked the wiring and sensors and all look ok. Then I decided to disconnect the battery in order to get rid off the engine light but more codes came back this time after I did that,
P1646, P1229, P1582,P1260,P0171,P0174. P1111.
so at this point I’m giving up , don’t know what to do next. The car runs fine that’s the part I don’t understand.

any advice of how to tackle this issues would be appreciated,
thanks 😊