SES code Evap imision controls (fixed)
My 1999 Park Ave (L36 naturally aspired) SES light came on today. I took it to Advanced and they said it was Evap/ Service engine soon.
Checked the gas cap and it was on nice and tight.
Opened the hood and noticed an odd sqealing sound , sounded like a fan belt but when I checked with a stethoscope it became clear the noise was not coming from the front of the engine. In order to get a better look at the situation I took off the plastic cover that sits on top of the UIM. As soon as I removed the oil fill extension the sqealing noise stopped and the engine idled very rough, it tried to stall . Put my hand over the oil fill on the valve cover and I could feel a noticable vacuum. When I seal the opening with my hand the sqeal comes back and it idles normally.
Any ideas on what might be going on?