Faulty Lambda sensor - location?

[Horrgakx]

I have a fault on a Lambda sensor which is intermittently throwing this error. Looks like it's in Bank 3, S1 (whatever S1 is). Does anyone know where abouts it is, as I'll need to ask the garage to change it.

24416 - Linear Oxygen (Lambda) Sensor B3 S1; Pump Current Wire
P3164 00 [11101000] - Open Circuit
MIL ON - Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 9
Mileage: 120402 km
Date: 2025.03.11
Time: 16:25:46

Engine speed: 1229.00 /min
Normed load value: 36.9 %
Vehicle speed: 51 km/h
Coolant temperature: 60 C
Intake air temperature: 12 C
Ambient air pressure: 1020 mbar
Voltage terminal 30: 13.853 V
Unlearning counter according OBD: 40
Engine torque: 227.5 Nm
Fuel level: 49.00 l
Intake camshaft B1 active operating state: 1