What should you check first if you see a low air pressure indicator while driving?

When you see a low air pressure indicator while driving, the first thing you should check is the air system. This is critical because the air pressure in a combination vehicle's braking system is essential for safe operation. A low air pressure indication may suggest that there is a problem with the air supply, which can lead to a loss of braking power.

The air system typically includes components like the air compressor, air tanks, and lines that deliver compressed air to the brakes. If there’s a malfunction in this system, it can significantly affect your ability to stop the vehicle safely. Therefore, addressing the issue in the air system should be your priority.

Checking fuel level, tire pressure, or engine temperature, while important, does not directly address the immediate safety risk presented by low air pressure in the braking system. Prioritizing the air system ensures that any potential safety hazards are mitigated right away.