P1456 Honda Odyssey: Understanding and Solving the Error Code

Are you the owner of a 1999-2001 Honda Odyssey experiencing a P1456 EVAP code issue? Dr. D from the Car Doctor Studios in Anchorage, Alaska has some helpful information for you. Watch the video for a detailed guide to resolving this problem.

If your 1999 Odyssey with a 3.5L VTE engine has a P1456 code set, it could indicate a leak on the fuel tank side of the evaporative emission system. To test the EVAP system, follow these steps:

  1. Scan the fuel tank pressure sensor voltage or test it with a digital voltmeter.
  2. The fuel tank pressure sensor has a three-wire connector located by the canister on the bracket. The light green wire connects to the fuel tank pressure sensor signal circuit.
  3. With the fuel cap removed and the ignition key turned on, the voltage should be close to 2.5 volts (zero pressure). With the fuel cap on, the voltage should increase to 2.8 to 2.9 volts as the fuel tank builds pressure when the engine is running.
  4. If there are no leaks in the fuel tank area or the fuel cap and the voltage doesn’t decrease after shutting off the engine, clamp off the hose from the bypass solenoid and two-way valve assembly that runs to the charcoal canister.
  5. Verify if the fuel tank holds pressure under these conditions. If it does, you’ll need to replace the two-way valve and the bypass solenoid and then retest the system. If the leak remains, use a smoke machine to check for leaks in the fuel tank and filler neck areas. Another possibility is a loose or defective fuel cap.

Good luck with your repairs, and remember, Dr. D is your reliable source for car repair information to keep you on the road. Stay tuned for more updates by subscribing to our channel. Thank you for watching!

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