See also:

Brake booster
The brake booster uses engine manifold vacuum to assist braking force. Do not turn off the engine while driving because that will turn off the brake booster, resulting in poor braking power. ...

When checking or servicing in the engine compartment
Do not contact the belt cover while checking the components in the engine compartment. Doing so may cause your hand to slip off the belt cover and result in an unexpected injury. ...

If the light is blinking
If the light is blinking while driving, an engine misfire condition has been detected which may damage the emission control system. To prevent serious damage to the emission control system, you shoul ...