Use only Honda OE quality replacement Catalytic Converters to keek your Honda Odyssey in the best running condition. DriveWire sells only California legal Odyssey OBD-II Converters.
If your Honda Odyssey failed the emissions test due to high NOX, the EGR Valve is most likely the issue. If your Honda is running rough or has poor fuel mileage, replace the Odyssey EGR Valve and gasket.
The Honda Odyssey Oxygen sensor is a critical part of the emmision control system and should be replaced as soon as it fails. Make sure to check the Honda Odyssey diagnosics codes for proper replacement of the O2 Sensor.