On my 2006 XJ8L I suddenly got these 3 codes today. The check engine light came on within the first 20 minutes of driving. The car still ran perfectly for the remainder of the journey. If it were not for the illuminated check engine light I would not have known anything was wrong.
P0491 Secondary Air Injection System
P0174 Bank 2 system too lean
P0171 Bank 1 system too lean
Are all 3 of these related to the same cause? Any suggestions as to what to check?
Thank you for your knowledge.