Car dashboards used to be pretty simple.  You had your speedometer, RPMs, gas gauge.... and not much else.  That was pretty much it.

Warning Lights

Take a look inside a modern vehicle and one of the first things you will notice, particularly if you are used to older cars, is that the dashboards now contain a ton of information.  It's like a Boeing 737 cockpit inside them!  While we used to just have the check engine light, which could be diagnosed easily, we now have a plethora of different gauges and flashing LEDs.  We are going to go through each of the warnings that you are likely to come across, and the importance of each one.

The Check Engine Light

The check engine light, or CEL, is the most common one that you are likely to encounter.  Unfortunately it is also the most complicated, and can mean all sorts of different things.  It truly is an outdated technology, because it can range from something completely serious to imminent danger.

If you are driving and it comes, and the car still seems to drive okay, then you are usually okay to continue.  However, you should definitely get it scanned with an OBD scanner to figure out why it is on.  Also, if you just filled up your car with gas and it comes on, be sure to go make sure your gas cap is tightened, as this can trigger them when not fastened down far enough.

Sometimes though, the CEL will come on and continue to blink at you.  This indicates a much more serious problem.  If you have an OBD scanner in the car, pull over immediately and use it.  If you don't have a scan tool handy, and the car still seems okay, keep driving, but immediately change your destination to the closest Autozone, Advance Auto Parts, Pepboys, or any store or mechanic service center.  Any place that has a scan tool is now your priority.  Most places will do free scans, and even if they charge you, $50-100 for a scan is cheaper than $5000 for a new engine.

The ABS / Brake Light

Unlike the CEL, the ABS light is much more specific.  This means there is a problem with your car's anti-lock brake system.  Although modern ABS systems are pretty complex, it is usually one of only a few different things.

ABS Light

When this light comes on, don't panic.  All this means is that your car now has "normal" brakes.  The brakes should behave the same that they do all of the time.  Unless you are in the middle of a snow storm, you aren't slamming on the brakes hard enough to trigger ABS in normal driving.

Usually if this warning comes up, it is one of these issues:

  1. The ABS fuse has blown.
  2. Your ABS module is bad.
  3. An ABS wheel sensor is bad.

In the case of #1, you can test this very easily.  Simply pop open your fuse box and swap your ABS fuse for another of the same type of fuse.  Make sure it's not anything important.  If the light turns off, you know it's the fuse, so just go buy a new one and you should be good to go.

As for #2, the module, this is pretty easy to test.  Check that no other drivers are around you, and slam on your brakes.  Usually, though not all the time, if you don't feel any pulsing, it is because your ABS module has failed.  While new modules can be expensive, you can usually just get your existing one rebuilt by electronics companies.  The cost generally is about $100-200.

Problem #3 is probably the most common.  If you see the ABS light and are feeling pulsing in the brake pedal, you likely have a bad wheel speed sensor.  Each of your four wheels has a speed sensor.  Since one of them is not reading speeds, that wheel gets locked up since the car's computer registers it as not moving while the other 3 are.  Speed sensors are usually very cheap and very easy to replace.

The Coolant / Temperature Light

Now we are getting into the serious ones.  This light means business!  If you see something resembling this, you need to pull over IMMEDIATELY.  Get out, pop the hood, and check your coolant level.

Coolant Light

Overheating a car can cause all sorts of different problems, and all of them are expensive to fix.  We're talking thousands of dollars in damage.

It is very rare that this light will come on and just be a sensor.  If you check your coolant level and it is okay AND your temperature gauge is still at the midway mark and nowhere near the "H" for Hot AND you don't notice smoke coming from the engine AND you are feeling lucky... then continue.  Otherwise, it's time to call AAA.

The Oil Light

Oil Light

As unfortunate as it may sound, if you see this, the damage is usually done.  This is right up there with the coolant light in terms of seriousness.  When you see it, pull over NOW.  This doesn't mean "try to make it to your destination".  It doesn't mean "stop at the next exit".  It means pull over 10 seconds ago.  The second you see this light you need to be hitting the emergency flashers button, pulling off the road, and shutting off the car.  Often times you have only seconds to do all of this before your engine is toast and you are paying $5000 for a replacement.

Unless you want to grenade your motor, or go shop for a new car with a significantly lowered trade-in value, take this seriously.  If this light comes on, you need to get over and check your oil level.  Chances are you don't carry 4+ quarts of oil with you at all times, so that means you almost certainly need to call a tow truck and get your car moved to the closest service center, or home if you are a DIYer.  Although if you are a DIYer, you probably realize the importance of lubrication in your engine, and didn't need this rant on oil lights.


Lastly, read your owner's manual.  These lights may look different depending on your specific vehicle, and you want to be aware of that.  You also probably have other model-specific warning sensors, and it's important to be aware of them.  Your owner's manual will explain in detail the functions of each, and how serious they are.  If you want to avoid expensive repairs later, take a few minutes and read about these warning lights.