How to fix antipollution fault 4 peugeot 307,2002?

I have had a problem with car nearly 10days. Mechanic said something wrong with a coil causing antipollution fault happened. But when mechanic replaced a coil,antipollution fault still happens again. The school nearly starts and my car is not ready for dropping off and picking up my children 4 school. Do you know the best way to fix it? Or you know any garage can fix it?