I have had this issue since this summer I had this issue for a bit of the P0140 code and I know that is the O2 sensor after the catalytic converter, but this code came up for Mass Air Flow (MAF) Circuit Low Input in the last couple of days. I checked the wires on it and they are attached and clean. I checked the air filter and it was pretty clean. The maf was clean too. The weird thing is that the entire air pipe from the engine to the air filter smells like gas. What should I do?