What is the emission system problem on the honda accord 2018?

If Your check emissions system light turned on in Your 2018 Honda Accord that usually means that there was a problem detected with the emissions system. It can be something as simple as a small vacuum leak, all the way up to problems with Your catalytic converter. To get a better idea of what is wrong with the car You should attach an OBD II scan tool and allow that to read the code that is in the ECU that made the light turn on. The most common reason it will turn on in a 2018 Accord is when You have a problem with the mass air flow sensor. Always check the wiring to it to make sure that it is in good shape when that light comes on.