'00 Odyssey LX - Codes P0420, P1457

[Markz]

Well, I've been searching around the board for some answers to the codes my 2000 LX just gave me today.

Actually, the CEL has been on for about two years now. An incident in 2008 involving running over a blown semi tire ripped the cat's O2 sensor out. I changed that sensor after the CEL said some code (I don't remember what code it was in particular) and the code went away for a short period of time, then came back. Up until now, the light has been on - I and a mechanic assumed the computer had been shorted out (which even today I'm still skeptical about) by the accident involving the tire. Our assumption is that there's nothing wrong with the sensor, and that the computer just thinks there is...

Which seems kind of stupid, but I've been neglecting the light for two years now - my bad.

Anyways, just today I decided to scan with my Actron, and got P0420 and P1457. I searched about the P0420 code and came up with possibilities like the cat might be clogged and may need to be replaced. I read about the temporary workaround for this problem involving modifying the mount of the cat O2 sensor and stuff, but since I'm due for inspection already, I was wondering if there's an actual way to resolve this code.

Also, there has never been any work done to the EGR system. My Odyssey currently has about 196,500 miles on it. Original transmission, heh.

Anyways, about P1457. A friend mechanic of mine works at a shop and says that he's had many 2nd-gen Odysseys come in that had various codes relating to EVAP work he eventually performed. I have read a bit about this code and possible fixes for it, but I'm real confused. I've read dozens of possible components that could be the cause, but one that sticks out is the EVAP bypass solenoid or valve or something (sorry). Can anyone verify this?

My Odyssey is already due for inspection. As I've done in the past with my other cars, I pull up to the testing station (free, and I'm cheap like that), clear any codes with my Actron scanner hoping they don't come back in the time it takes for inspection to complete, and go through with flying colors. But any help on these two codes I have on my Ody would be greatly appreciated.

[William Wiles]

O2 problems can be checked with an OBDII scanner. P1457 is a leak in the evap system. Could be any of several valves or hoses. P0420 is cat efficiency which is a check made by comparing the secondary O2 senser to the primary senser. The O2 xensers can be checked out with an OBDII scanner as I said.
I take it your inspections were all tailpipe inspections and not with an OBDII scanner as most inspection stations do now. Resetting the PCM resets half a dozen readiness circuits and it takes several drive cycles for them to complete. This is a failure in all the inspections I have seen. It could take several days for them to set.