Equinox Intake Manifold Flap

The symptoms you describe point towards an issue within the intake system, specifically the intake manifold flap control. Did the fault code reader provide a specific diagnostic trouble code (DTC)? Knowing the exact code would help determine the root cause more precisely. Considering the symptoms and mileage, the intake manifold flap control switch could be defective. Before replacing the switch, verify the wiring harness and connectors for damage or corrosion. A vacuum leak could also mimic these symptoms. Have you inspected the vacuum lines for cracks or disconnections?

The code is P2015. I haven't checked the wiring harness yet, but that's next. Where should I look for vacuum lines?

P2015 confirms a problem with the intake manifold flap position sensor/switch. Given the age and mileage, the switch itself is likely faulty. Inspecting the wiring and vacuum lines is worthwhile, but the P2015 code strongly suggests internal failure of the flap control mechanism or its sensor, often integrated within the intake manifold. Considering your expertise level and the potential complexity, I recommend a professional diagnosis. The hissing sound could indicate a more significant leak, potentially affecting the turbocharger system. Taking it to a reputable workshop would be advisable.

The intake manifold flap control switch was indeed faulty. They replaced the whole unit, and with labor and parts, it cost about 465€. But, she's running great again. No more hissing, jerking, or feeling like I'm towing a boat anchor.