Opel Astra-J 2011 1.6 Misfire

Hello Professionals

Astra-J 2011, 1.6
VIN: W0LPC6ED5B8000468

This vehicle has one fault code stored which is P06A3.
The symptoms are misfire. I assume a lean misfire because lambda values are very low, the previous workshop has changed the engine.
Any advice on what to check? I am in the dark as I have no wiring diagrams or technical info.
Attached is the fault.

Thanks.