the hole that the sending unit was covering was removed for about 2 hours(used a rag to cover it up)but there was a full tank of gas in there. When the gas went down to about 3/4 tank, the light came on. Could this be because of air being in the tank? It‘s been 3 days, so how long should I drive before taking it to the mechanic? everything else works just fine
you need to put year/make/model it's very important. so the guess if your car is 1996 or newer, you could have a loose fuel line, as the tank gets pressurized, the computer checks for that pressure. if it doesn't detect it, it gives the check light on. Usually it's the gas cap at fault, but in this case, it could be the lines.
take the battery cable off then replace it the light will go off.
The problem is most likely due to an air suction leak into the fuel system, which the computer recognizes as a fault in the engine's evaporative control system. The code will have the term gross evaporative loss or similar (generic code P0440 on OBD II systems). - I suggest you re-check all your work, and ensure that the connections to the tank, and the fuel sending unit gasket into the tank are secure. Once the problem is repaired the MIL should go off within 2 days of normal operation.
