Any vehicle owner who’s ever seen their check engine light come on knows the dreaded, sinking feeling in the pit of their stomach at the sight of it. While some people may ignore the light in an attempt to avoid a potentially costly vehicle repair, one thing’s for sure – the check engine light is one warning you should never ignore.
This warning can show up for any number of reasons – some minor, some severe. Occasionally, the light could come on when nothing is wrong with the vehicle at all, like from a temporary shift in humidity, or a loose gas cap.
In these cases, the light should turn off after a period of time (or if you re-tighten the gas cap if that’s the issue). However, it is typically indicative of a problem, so don’t assume you’re in the clear!
Sometimes the light will flash rather than remain steady, which indicates a problem of severity that needs immediate attention to avoid catastrophic engine failure.
To find out what the source of the problem is, a device will be used by the mechanic to read the check engine light’s diagnostic trouble code (DTC). While these code readers are available for purchase to anyone (and many auto DIYers own them), we still issue caution in diagnosing the vehicle problem yourself.
The reason? A code may tell you, for example, that you have a problem with a particular sensor in your car. You may go out and purchase a new sensor, ready to install it, and save yourself a trip to the auto shop.
However, upon starting the work, you discover that the sensor itself is fine, but the wires connected to the sensor are corroded and caused the light to come on.
Now you’ve purchased a part you don’t actually need, and wasted time that could have been saved had the issue been properly diagnosed by a professional. That’s just one example of how easy it is to misdiagnose a problem, even when you have a DTC available.
While tons of things could cause this light to turn on, the five most common check engine light codes in order of frequency are: