Q: Dodge Neon SE 2003 problem is code P0440

The trouble code P0440 means the Evaporative emission control system is malfunction. This malfunction may have been caused by a number of different things including, a loose or missing gas cap, a vacuum leak, a faulty purge valve, an issue with your charcoal canister, incorrect fuel pressure, or electrical issues.

I would recommend having your entire EVAP system inspected by a mechanic who is proficient in diagnosing emissions issues. The most likely cause of this issue is either a loose gas cap or a vacuum leak.

Sometimes the issue is very obvious and may be spotted just by opening the hood. It is possible that a hose may have come loose causing the trouble code to be stored and the Check Engine Light to come on. For a proper diagnosis, consider YourMechanic, as a certified technician from YourMechanic can come to your car’s location to inspect the Check Engine Light and make proper adjustments or repairs.