The Code Reader takes common DTCs, breaks down when and why they occur and looks at symptoms and causes to help listeners make an accurate diagnosis.
Our scan tool pulled a diagnostic trouble code of P0455: Evap System Large Leak Detected.
P0455 is a common EVAP trouble code and one whose description quite often accurately reflects what is causing the problem. The purpose of the evaporative emission system is to prevent the fuel vapors in the gas tank from escaping into the atmosphere and when this code sets, it’s a good bet that they are.
These systems have the ability to approximate the size of a leak, and in the case of P0455, pretty much the first thing a technician is going to do is check the gas cap to make sure it is present and properly installed. Although not necessarily the problem, a missing gas cap is a perfect example of the size of leak that would cause P0455 to set.
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