Hi my mechanic has advised me that the bank 2 sensor 2 knock sensor on my car (Bentley Continental GT 2010) is defective. Can you advise how much is it to replace and also the bank 1 air flow meter. The two codes he has given me are C00586 knock sensor 2-bank 2 (G199) and C00511 Engine Management Control Module - bank 1. Will the engine be required to be removed to fix the sensors?