I am new to the forums here. I have a 2006 XC90 T5. 110K. I bought the car about a year ago and it has run great. About two months ago I got a CEL. I had it checked and the codes were p0026 and p0172. My mechanic told me to try and fresh oil change and go from there. I got the oil change and the light reset. It stayed off for about a month and not it is back on. Same codes! I purchased a used intake solenoid and new gasket. I replaced them but nothing changed. I cleaned the original very well and made sure it was actuating. ordered two gaskets so I put the original back on. Still getting the same codes. I have no idea where to start now. Any thoughts or advice would be great. Thanks in advance.