The first thing to do when a low air pressure signal comes on is:

• A. Stop and park as soon as possible
• B. Check the air filter
• C. Continue driving to a service area
• D. Reset the warning lamp

Answer: (B)

When the low air pressure signal comes on, the system isn’t delivering the required braking pressure. A common and quick cause is a clogged air filter that restricts air entering the system, which can trigger the warning. Checking the air filter is the best first step because it’s a simple, fast check you can perform on the spot, and if the filter is dirty, replacing it often restores proper pressure without a major delay. If the filter is clean, you’ll need to continue diagnosing other parts of the air system, but ruling out a dirty filter first addresses a frequent, easily fixable cause. Resetting the lamp won’t fix the underlying issue, and continuing to drive with low pressure can be dangerous, so treat the air filter check as the initial, practical move.