Emissions light - when will it go off?

[Pep]

Had my car on a diagnostics yesterday, said my Pre cat lambda was mashed, just replaced it and the light is still on.

Does it need to be cleared on a machine again, or will it take a certain amount of time to turn off etc?

 

[TOGUSA]

you need to clear it with a machine, the fault is still logged on the computer untill you clear it,
can be done using any obdII device capable of reading and clearing faults

 

[Pep]

OK cheers mate, I'll have to find somewhere local to do it.