What does it mean when my engine light is on?

Car engines for the past couple of decades have had increasingly sophisticated on-board diagnostic systems, or OBDs, that give car drivers warnings when they spot problems that the system can’t fix itself. When this happens, you will see a specific warning light on the car’s dashboard to alert you to the problem. Below is a list of possible lights you can see, and what they might mean.

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1. Check Engine Light

This is the general “check engine” warning light. If this light comes on, and it is not blinking, there are a number of both common and uncommon meanings, such as the following:

  • Oxygen sensors
  • Fuel cap
  • Catalytic converter(s)
  • Spark plugs and wires
  • Mass air flow sensor
  • Ignition coil(s)
  • Battery and alternator system
  • Exhaust gas recirculation valve
  • Vacuum hose

If the ‘check engine’ light is blinking, it usually means there is a much more serious problem and you should have it looked at by your mechanic as soon as possible.
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2. Brake Warning Light

If this light comes on and does not go out, it usually means one of two things:

  • You still have your emergency/parking brake on
  • The braking system has lost a significant amount of pressure

It’s easy to take off the parking brake, but if you’ve lost pressure in the braking system you should bring it in to be fixed immediately.
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3. Battery Warning Light

If you see this light come on, it typically means there is an issue with the alternator system that recharges the engine’s battery. Your vehicle will be able to continue operating for a while without being recharged, but when the battery eventually dies all of the electrical components in your car will shut down: the engine will turn off, and you won’t be able to start it back up again. It’s important to take your car to a mechanic as soon as possible so it can be fixed.

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4a. Engine Temperature Warning Light

This symbol is meant to warn you that the temperature of your engine is too high. There are two quick and easy short-term solutions to help cool the engine off:

  • Turn off the engine and keep it off for a bit
  • Turn on the heater to the highest setting

This won’t fix any underlying issue causing the engine to overheat, however, and you should take it into your dealer/authorized car service to have it looked at and repaired.

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4b. Engine Temperature Warning Light

If you see the same symbol in blue, meanwhile, it means the exact opposite: the coolant temperature is below the ideal range for optimal performance.

Alternatively, if this light blinks red and blue at the same time, it usually means that the cooling system has an electrical issue. With either case, you should bring your car in to properly diagnose and repair the malfunction.

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5. Oil Level/Pressure Warning Light

This symbols is meant to warn you of an issue with the engine’s oil level or oil pressure. The engine either has a dangerously low amount of oil, or the oil pressure is dangerous low. Both are critical issues that should be addressed as soon as possible or the engine could suffer serious damage.

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6. Service Light

This light is most often just a reminder that the car is close to being due for a routine service appointment, such as a change of oil and oil filters.

In more rare circumstances, it could also suggest a more serious problem. On more recent vehicles it might include additional text referring to a specific system. Either way, you should contact the service department to arrange to bring your car in for inspection and repair.