Charge Pressure probs

[ChipHazzard]

Gent's

A recent scan showed the following problem

17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-10 - - - Intermittent

I cleared the fault and went out for a spin and all looked good as the code never reappeared, however I went out for a spin tonight and the car felt very lifeless again so I ran another scan which showed the following problem

17964 - Charge Pressure Control: Negative Deviation
P1556 - 35-00 - -

the compete opposite of the original problem. All suggestions are greatfully accepted and having looked back thru past post I'm guessing either a boost leak or something else

Thanks in advance

Mike

99fl Noggy S4 Avant