which O2 sensor driver side, and which passenger?

[V1nny]

Noticed last week that my 2001 Allroad with 3-minus tune is way too thirsty, run a quick scan, and found bunch of codes:

Address 01: Engine Labels: None
Control Module Part Number: JFonz Tuning
Component and/or Version: 2.7tt /5VT 0002
Software Coding: 06711
Work Shop Code: WSC 87119
2 Faults Found:

17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-00 - -
17521 - Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent

Readiness: 0010 0000

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Cleared the codes, drove about five miles to the gym and back, scanned again:
Address 01: Engine Labels: None
Control Module Part Number: JFonz Tuning
Component and/or Version: 2.7tt /5VT 0002
Software Coding: 06711
Work Shop Code: WSC 87119
4 Faults Found:

16534 - Oxygen (Lambda) Sensor B2 S1: Malfunction in Circuit
P0150 - 35-10 - - - Intermittent
17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16688 - Cylinder 4: Misfire Detected
P0304 - 35-00 - -

Car drives pretty good, lots of power, but mileage is really poor, exhaust smells like I running slightly reach. So I am ready to replace the two oxygen sensors. If anyone knows which side is B1 S1 and/or B2 S1? Do I even need to change them both? Universal 4-wire vs. more expensive OEM part? Anyone maybe happen to have them for sale, or knows a good source?

[Audi_Tech]

Bank one (B1S2) is passenger side, bank two (B2S1) is drivers side. Sensor one (B1S1) is front oxygen sensor and sensor two (B2S2) is rear oxygen sensor.

PM VIN for price on OEM sensor(s).