For many drivers, it’s their worst nightmare in terms of vehicle maintenance: the check engine light pops on in the dashboard. When this engine warning light comes on, a whole lot of those who are relatively inexperienced with cars can get a little panicky, wondering just what they’re supposed to do to make sure their engine doesn’t blow up. The reality is that a check engine light signals a vast range of problems and sub-optimal conditions in an engine, and without other symptoms, the odds are low that a check engine light, especially on a modern vehicle, means breakdown is imminent.
One of the first things that drivers should do when they see that check engine light is to stop the vehicle and take a look at the owner’s manual. Although check engine lights on many vehicles don’t do a very good job of showing what the problem is, some vehicles have two different “states” of engine trouble, where a solid engine light signals more minor problems, and a flashing engine light means there’s big trouble ahead.
Besides reading the manual, one essential response is to check the engine oil level. A check engine light could mean that oil pressure or oil volume in a vehicle is low. This is one of the relatively few issues that will actually cause the engine to quickly seize up and destroy itself while the vehicle is on the road. Low engine oil is a serious problem, and ruling it out can help assure the driver that a vehicle with a check engine light can make it home safely. However, drivers will also want to check for any other symptoms, such as loud engine noises, hot smells or other danger signs, and use good judgment in deciding whether to drive the vehicle home or get it towed.
Most modern vehicles use new computerized tools to diagnose engine problems. The vehicles have a system called OBD, or On Board Diagnostic, that can sense various conditions under the hood. Small “reader” units deliver a trouble code: these can be bought at auto supply stores. Some shops also test your engine computer for free.
The problem is that even the trouble codes delivered by an OBD reader can be somewhat vague. At best, the OBD code narrows down the problem. It’s still up to the driver and expert ASE certified mechanics to figure out what exactly is wrong.
There is a lot that a driver can do to help diagnose their own check engine light situations. Most of this involves reading about the OBD system and various trouble codes, and understanding how a trouble code relates to the specific component of a vehicle. In doing this, drivers will also learn more about how to figure out if a check engine light represents a fuel economy problem or something worse.
It’s important to note that in some cases, a check engine light can simply be “flagged” on by different temporary conditions. In these cases, some drivers simply disconnect the battery, and wait until the check engine light is “cleared.” Then they continue driving. If the light does not come back on after over several dozen miles, there’s a good chance that the problem was a false flag. However, most drivers prefer to have an expert shop do a diagnosis and fix what’s wrong with the vehicle.