Oil leak - please help!

[Shankmeister]

I have a 2010 S212 E350 CDI BlueTEC. My engine management light recently lit amber. Around the same time, the transmission started getting a bit clunky/jerky.

I bought an OBDII reader to use with my phone. It reported the following:
Car Scanner ELM OBD2
DTC report
Selected brand: Mercedes-Benz

============1==============
P2454
Raw code: 2454
ECU: Engine control unit
Status: Confirmed
OBDII: Diesel particulate filter (DPF) pressure sensor A - circuit low

============2==============
P2453
Raw code: 2453
ECU: Engine control unit
Status: Pending
OBDII: Diesel particulate filter (DPF) pressure sensor A - circuit malfunction

============3==============
P11DA(00)
Raw code: 11DA00
ECU: Engine control unit
Status: Test failed, Test failed (current drive cycle), Pending, Confirmed, Test failed since last DTC clear, Warning indicator requested

============4==============
P1297(00)
Raw code: 129700
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear, Test not completed during this operation cycle
OBDII: Injector High Sides Shorted Together

============5==============
P14D8(00)
Raw code: 14D800
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear

============6==============
P118A(00)
Raw code: 118A00
ECU: Engine control unit
Status: Pending, Test failed since last DTC clear, Test not completed during this operation cycle

============7==============
P11A7(00)
Raw code: 11A700
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear

============8==============
P11D9(00)
Raw code: 11D900
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear

============9==============
P11DA(00)
Raw code: 11DA00
ECU: Engine control unit
Status: Test failed, Test failed (current drive cycle), Pending, Confirmed, Test failed since last DTC clear, Warning indicator requested

============10==============
P131E(00)
Raw code: 131E00
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear

============11==============
P118D(00)
Raw code: 118D00
ECU: Engine control unit
Status: Pending, Test failed since last DTC clear, Test not completed during this operation cycle

============12==============
P10BB(00)
Raw code: 10BB00
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear

============13==============
P1218(00)
Raw code: 121800
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear
OBDII: CID High

============14==============
P1219(00)
Raw code: 121900
ECU: Engine control unit[Archive (inactive)]
Status: Test failed since last DTC clear
OBDII: CID Low

A bit of Googling led me to believe that I needed to replace the manifold pressure sensor so I ordered this: https://www.amazon.co.uk/gp/product/B01LF7Q64A/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Today I lifted the bonnet to attempt to fit it. On removing the plastic engine cover, I discovered that there appears to be an oil leak per the photos below. Is anyone able to advise me what the source of the leak is?