My check engine light keeps returning. Codes are

Oxygen sensor B2 S1
P1197-Electrical malfunction

And

Oxygen sensor B2 S1
P2247-Reference voltage open circuit

I replaced oxygen sensor bank 2 sensor 1 with Bosch upstream replacement from FCP euro. Codes returned after a few starts of the engine. I took the car to Volkswagen dealership for help and they said some oil had gotten into the connector housing and replaced the housing for connector. Again, drove it a few times and check engine light returns. Same codes. I also sprayed connections with contact cleaner several times and same thing happens.

Please help if you know anything. I’m thinking it could be a possible ground issue.