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Q: Code P0456

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Evaporative Emissions System - Small leak detected. As you know this vehicle has no gas cap. I tried to clean the filler flap, clear code but it returned again.You have any ides Thanks John

My car has 42122 miles.
My car has an automatic transmission.

Hi, thanks for writing in. I’d be happy to help.

The P0456 code is for a small leak and the only way to find such a small leak is to have the system pressurized using the test port under the hood. The system is pumped full of a smoke that has a special dye in it that will show up with an ultraviolet light. Once the leak is detected then you can repair it as needed. The fuel fill valve and the purge valve under the hood is the two main areas that leak the most. This test will isolate the leaks for you and should be done before replacing any parts.

If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make any repairs as needed.

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