P0441 hit me the other day

If it's the evaporative emissions control system, it typically takes a few drive cycles to set or clear the light. If you manually clear the code and it doesn't return, problem solved. Since you found a gas cap loose, that is the likely cause of the problem (and is the most common cause of this problem).

The system pressurizes the fuel tank and checks that the pressure holds. If not, then there is a leak that can allow fuel vapors to escape to the atmosphere, which is the problem the evap control system was installed to prevent. The ECM detects this and puts on the check engine light and stores the code.

There are a number of things in the system that can fail or deteriorate, anything from the loose cap to a loose or cracked fitting, etc. Estimating the cost is impossible unless a problem is identified. If the code returns and your gas cap is tight, and you desire to fix the problem, take it to a good shop for a smoke test. They put a smoke generator connected to the evap system and see where the smoke leaks out.

 

Was this in response to the OBD code?

 

I don't understand this.

 

Got it. I've been living with an intermittent evap system code on my 2006 MX-5 for a few years. It comes and goes, and it's not worth fixing. Lately it's gone more. Doesn't affect driveability, so I just live with it.