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Q: What are the three hoses coming from air box on my Buick verano?

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My Buick verano has three hoses coming from the air box. One is a vacuum line, I believe one goes to the pcv valve, and the 3rd goes back to the firewall. When that 3rd hose is removed...it is sucking air from what appears to be the firewall. What is this?

My car has 90000 miles.
My car has an automatic transmission.

Hello, thank you for writing in. There are several vacuum lines associated with the engine intake and throttle. One of which that does run along up towards the firewall is the brake booster line. This vacuum helps assist the master cylinder in maximizing the brake assisting. The others are for the EVAP canister, the fuel pressure regulator, super charger if equipped, and manifold pressure source. You will find the best sources for diagrams is in repair manuals for the vehicle. You may also want to locate the component on the other side to see what the purpose of this line is. For more diagnostic help, contact our service department to schedule an appointment.

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