I have gotten CEL about 3 times in the past 2 weeks occurring only in the morning after the car has sat all night in my garage. The last CEL included 4 misfire codes in the 1,2,4 & 6th cylinder banks, along with P0491 and P0492 codes. The car runs fine and strong in the afternoon when I go to lunch and on the drive home, i.e. full boost at 1.2 bar with no hesitations. No issues, I just clear the CEL codes. I have also noticed what sounds like a low muted, high pitched whine in the morning that disappears after the car warms up. I notice this sound more so when the a/c is left turned up high from the day before. Any ideas guys? I think it's a boost leak somewhere and will be getting under the car to look for a loose hose this weekend. Is there any way to check for a leak with an air compressor? Thanks in advance for your comments.

 

P0491, P0492
Secondary Air Injection System, Bank 1, Bank 2 – Below Limit

Possible fault cause
♦ Secondary air injection pump is not triggered
♦ Secondary air injection pump does not work
♦ Air supply lines restricted
♦ Electric change-over valve does not function
♦ Air change-over valve does not function
♦ Vacuum system leaking