What action is recommended if there is a loud air leak from a trailer line while driving?

Answer: B — Safely pull over and inspect for leaks or damage.

When the air brake system shows a loud leak from a trailer line, the immediate concern is loss of braking pressure. A strong hiss usually means air is escaping, and that can quickly reduce or cut off the trailer’s braking capability, creating a high risk of a crash. The safest move is to stop as soon as it’s safe and inspect for leaks or damage. This lets you identify a loose connection, damaged hose, or broken line and decide whether it can be repaired on the spot or if you need assistance before continuing. Continuing to drive with a loud air leak is unsafe because braking performance can deteriorate unpredictably. Turning off the engine may drop air pressure further and isn’t the best first step; you need the system pressurized to assess and address the leak. If you need help after you’ve safely stopped, call for assistance.