Hello I have a question my CEL comes on P0430 i have an emmision test coming soon if i clear the code before the test will i be able to pass?

 

Depends on your local emissions test procedures.

When you clear the code using an OBD2 scanner, it also clears the "readiness monitors" which is basically parameters that the car sets up after being run for several drive cycles. If there is some sort of problem, it will catch it in this period of time and throw a check engine light.

I know some states will not allow a car to pass if the readiness monitors are recently cleared and haven't been reset, because that's usually a tell tale sign that a check engine light has been cleared to try and sneak it by.

On the flip side, some states don't give a damn, and others don't even care if the check engine light is on at all.

 

O2 monitors need to have been run for it to pass emissions. Evap codes are the only ones that aren't required to have run in most states to pass. You most likely have a small exhaust leak somewhere but you might be able too cheat the computer by installing O2 sensor spacers on the rear O2s.

 

P0420 or P0430 is almost always caused by a crack somewhere between the Primary CAT and the downstream O2 Sensor.
Could also be the gasket in between the flanges leaking of else a split in the flange itself.
That crack lets fresh air into the exhaust which adds oxygen and throws the O2 sensor off.

Get an exhaust specialist to take a look at it. If the crack is in the welds for the flange on the Y-pipe side, then sometimes they can weld it.
On mine I ended up getting the whole section from the flange to where the 2 sides join, but kept the OEM downstream CAT.
Cost me $250 and was done in an afternoon.

We have to get this type of problem fixed here as our annual inspection (MOT) requires that no error codes be shown on the dashboard.