Gas Cap
Purge Valve
Vent Valve
The necessary parts and tools to clear this Diagnostic Trouble Code (DTC) might differ depending on your vehicle's make and model. If your Check Engine light is illuminated, stop by any O’Reilly Auto Parts and get an O’Reilly VeriScan® for your car, truck, or SUV and get a detailed VeriScan report with more information about your vehicle’s Diagnostic Trouble Code(s), along with possible causes and repair solutions. If you aren’t comfortable making these repairs yourself, our parts professionals can recommend a local shop to make your repair.
OBD-II fault code P0456 means “Evaporative Emissions System Leak Detected”, but refers to only a very small leak in the emission system. This means that somewhere between your gas cap and your engine, a small amount of fuel vapor is escaping. The evaporative emissions (or EVAP) system pressurizes the fuel tank and lines regularly to test for leaks, and if pressure loss is detected, you may experience this code. If your evaporative emissions system is experiencing a large leak, this would instead be indicated by code P0455.
P0456 Code Diagnosis
When you experience a P0456 diagnostic trouble code, your vehicle may be experiencing failure in one of a few areas:
- EVAP hose leaks
- A faulty or damaged purge valve
- A damaged vent valve
- A loose or leaking gas cap
It’s recommended that you always begin diagnosing any EVAP system leak by making sure your gas cap is secure and sealing properly. Many gas caps are designed to click several times when they are fully tightened, so remove your fuel cap, inspect it for signs of damage, and tighten it back fully to determine if this may have been the source of the problem.
EVAP system leaks are often very difficult to diagnose, especially with small leaks. In many cases, professional diagnostic equipment may be necessary. Repair facilities often utilize smoke machines or other equipment to pinpoint the source of the leak visibly so that it can be properly repaired. If you would prefer to have your vehicle professionally diagnosed, we’d be happy to recommend a trusted local service center in your area.
P0456 OBD-II Code SymptomsThe only symptom you may experience with a P0456 code is a Check Engine light, as a small EVAP leak is not typically enough to cause noticeable performance issues.
It is okay to drive, but it’s important to have any EVAP leaks diagnosed professionally or make any necessary repairs as soon as possible.
