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Hey All,

Just bought a 2006 Civic LX with 220k. During inspection it had P0420 but inspection person said it needed further research to know what exactly was causing it.

Connecting laptop to OBD2, these are the reading.

Anyone know if this indicates either Front or Rear Sensor, of its the Cat converter?

Emissions passed with flying colors despite P0420code.

Thanks for anyones help.

 
Rep Power: 221

Rear o2 checks the cat. Cat is probably bad. Does the code come back fairly quick or does it take a bit? You can try some of the cat cleaning stuff you put in the gas tank. I had it work on a car with an intermittent p0420. Or throw an o2 spacer on.

 
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Yeah after resetting CEL, it came back in the 2nd 2 20 min drive.

Does the data i posted indicate O2 sensors working just fine?

 
Rep Power: 221

Sure.
Try a couple of bottles of the snake oil through the fuel system. If the code still comes back try a spacer on the rear o2.

 
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Where are you that you were able to pass emissions with an active P0420 error code? Or was it active at the time?

 
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This was in Boulder, Colorado. The seller is supposed to do emissions testing here and he told us they didnt care about the check engine light as the actual emissions numbers were extremely low and very similar to 2 years ago.

 
Rep Power: 221

Can't remember if we (Ontario) still had etests at that point or not. If we did I got it to pass by driving until i had enough readiness monitors and testing it immediately with no check engine light.
if the emissions inspection only cares about the actual tailpipe numbers and not the check engine light i wouldn't worry about it.