What this code means
P2404 is a standard OBD-II diagnostic trouble code in the Fuel, Air & Emissions (Extended) category. Official description: "Evaporative Emission System Leak Detection Pump Sense Circuit Range/Performance."
How RootCause approaches a code like this
A code names what the computer detected — not which part is actually at fault. The same code can have several different real causes. RootCause gathers evidence — prior repair history, live sensor data, targeted tests — and ranks what's actually wrong before you spend on a guess, with an honest list of what the evidence argues against.
Try the evidence-based approach