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Q: Don't understand CEL Codes.

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Hello,

Recently my car's check engine light turned on, ever since then every time I attempt to turn on the car it has difficulty turning over. Here are the Codes: P0300 P0301 P0302 P0303 P0304 P0305 P0306 P1456 I attempted to search Google on the meaning of these codes and i get mixed messages. If someone can clarify what might be the problem that would be greatly appreciated. 2000 Honda Accord LX V6

My car has 230000 miles.
My car has an automatic transmission.

A: The codes P0300 through P0306 are for misfi...

The codes P0300 through P0306 are for misfires of random cylinders or different cylinders. The second code P1456 is for the evaporative fuel tank system having a leak somewhere in the system. Since you are getting random misfires, then I think you have excessive fuel tank fumes getting in the engine when the engine is not running or at idle when there should be no fuel tank vent fumes getting in the engine. The system should only let fumes into the engine at a cruising engine speed.

If the EVAP vent valve is leaking, then it will cause the leak and the code P1456. The misfire codes can be caused from the excessive fumes getting in the engine. You need to have the EVAP vent valve checked and the system smoke leak checked for leaks. Once the leak is found then the misfire codes should go away and the P01456 should be fixed. If you want to have this looked at, a technician from YourMechanic can come to your car’s location to inspect for leaks and diagnose your Check Engine Light so that all of the correct repairs are made.

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