Rifter Check Engine Light Air Valve

I had a similar headache with my old Volvo V70. The check engine light tormented me for weeks. It turned out to be a cracked vacuum hose connecting the pump to the air valve. These hoses can become brittle with age and heat. Is your check engine light illuminated constantly, or does it flicker? Maybe try listening for a hissing sound near those hoses; that's what I heard initially.

Thank you for your quick answer! The light is on constantly. Is the air valve essential? And where exactly were those vacuum hoses in your Volvo?

The air valve helps regulate the air-fuel mixture, so yes, it's pretty important. On my Volvo, those pesky vacuum hoses were tucked away near the air intake manifold, close to where the air valve was mounted. Tracing them was like navigating a spaghetti junction! My best advice would be to get it checked out by a professional; it could save you a lot of time and prevent further issues.

Thank you for all the information. I had my Rifter diagnosed. It was indeed the hose connection from the pump to the air valve that was defective. It cost me 175€ to repair but at least it is fixed. I really appreciate your help!