I have an odyssey with 140000 miles. I took it to Auto Zone and got these codes from them 0420, 1456, and 0300-0306. We thought it was the catalytic converter so changed it out but still having issues. It has a constant "rev-ing" and will only get 5000 rpms when pedal to the floor. Does anyone have any ideas??? Can't afford to take it to the shop, we are doing the repairs ourselves. It started the probs after filling the tank with gas and putting stp fuel additive in it. If anyone has any suggestions it would be greatly appreciated. Thanks in advance
Niki

 

here is what the codes meen

P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P1456 EVAP Emission Control System Leak Detected (Fuel Tank System)
P0300 Random/Multiple Cylinder Misfire Detected
P0306 Cylinder 6 Misfire Detected


Well was the ecu reset after installing the new converted ? I would check all of your spark plugs because you have codes for misfires , and a misfire on cylinder #6 , Your evap leak could be something as simple as a loose gas cap or a bad gas cap , also your 2way bypass valve could be bad giving the p1456 code, I hope this gets you in the right direction.

 

If a p1456 code on an Ody led you here:
I had the p1456 on my 2000 Ody, but the gas cap and down to the tank was clearly tight (pressure release when opened). The service manual tells you to start disconnecting fuel lines at this point, but some of the latter checks just require a voltmeter, so I decide to look at those first. Didn't even need the meter--under the hood by the driver side of the firewall, two ~#18 or 20 wires had left their taping on their way to the sensor. Where one of them rubbed against the car body rust had formed, but more significantly, the insulation had worn away. A little electrical tape, some protective cowling, and no more code.