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Warning Lights

Manufacturing costs often force auto designers to combine several warning signals in a single dashboard indicator, making it harder for drivers to understand the message.

The two most common warning signals – water temperature and oil pressure – are frequently combined in a single “engine” light. When the engine light comes on, drivers must expect the worst and turn off the engine immediately. With separate warning lights or auxiliary gauges, a driver can distinguish a minor overheating situation from a more expensive repair. All cars built since 1981 have a built-in self diagnostic system with a “check engine” or “power loss” warning light that provides a different warning than the “engine” light. “Check engine” identifies a malfunction in the computerized engine controls under the hood.

The “check engine” warning light does not call for emergency attention, but prompt attention can keep the situation from worsening.

The “brake” warning light can be confusing, too. It usually indicates that the parking brake is engaged. It also may indicate one or more of the following conditions depending on the type of car.

  • Brake fluid is low in the reservoir.
  • Power assist for the brake system has failed.
  • One of the dual braking systems has failed.

The alternator or charging system warning light checks only the presence of electrical “pressure”, commonly known as voltage, coming from the alternator. A loose drive belt can allow electricity to be present, but not in sufficient amounts to keep the battery charged.

To prepare for warning light conditions during driving:

  • Clarify the exact interpretation of your car’s warning lights by reading or re-reading the owner’s manual.
  • Plan a mental course of action in advance for what to do should a given warning light come on while driving.
  • Compare the owner’s manual of each car you own to understand the similarities and differences in warning lights that appear to be identical.
  • When shopping for a new car, consider optional gauge packages that make it easier to interpret warning light messages

When a warning light comes on while driving, do not reach for the operating manual and fumble through it for emergency answers. Read and understand it in advance, and then you can be calm and cool when the unexpected happens.