Peugeot Boxer air valve fault

I've had similar experiences with my Peugeot Boxer. If the check engine light is on, and you're suspecting the air valve, it is possibly due to a faulty hose connection between the pump and the valve. Inspect the hoses meticulously for any cracks or looseness. A small leak there can cause the check engine light to come on. Are you experiencing any noticeable changes in the engine's performance besides the light?

Thank you for your input! Besides the check engine light, the engine does seem to idle somewhat roughly at times, especially when it's cold. The issue seems to come and go, rather annoyingly. Could a small leak in that hose really cause such intermittent problems? Is it possible the air intake has some deposits? I'd greatly appreciate any further insight you might offer.

Indeed, even a slight air leak can lead to the issues you're describing, especially in older models where the system might be more sensitive. It's possible to remove the air intake and clean it yourself, but this requires knowledge of the engine. The intermittent issue is likely due to temperature changes affecting the hose's flexibility and seal, creating a temporary fix. I highly suggest visiting a workshop.

Thank you so much for the helpful advice! Based on your recommendation, I took the Boxer to a workshop. It turned out to be exactly as you suspected – a small crack in the hose connection between the pump and the air valve. Replacement and diagnostics amounted to 175€, and the check engine light is now off. I appreciate you pointing me in the right direction!