P2404: Evaporative Emission System Leak Detection Pump Sense Circuit Range/Performance
What to do
The car drives normally. Check the fuel filler cap is properly on and tight before anything else — a cap left loose makes the pump unable to build pressure and produces exactly this. Beyond that, this can mean the system is genuinely leaking, genuinely blocked, or that the pump has failed, and those need separating before a part is bought.
What this code means
The pump's sense circuit is reporting something the module cannot reconcile — the pump is running, but what it achieves does not match any pattern the module recognises.
The interesting cases are the ones where nothing electrical is wrong at all, because this circuit measures a physical outcome:
- The system is genuinely leaking so badly that the pump cannot build any pressure, in which case a large-leak code such as P0455 usually appears alongside and is the fault to chase. A fuel cap left off is the classic version.
- The system is blocked rather than leaking — a pinched vent hose or a canister saturated with fuel — so pressure rises far faster than expected, which is equally implausible and equally not a pump fault.
- The pump's own diaphragm has perished, which is a genuine pump failure and the only one of the three where replacing it is right.
So the order that saves money is to establish whether the system is sealed, leaking or blocked before concluding anything about the part that measures it.
Likely causes
Start here
- Loose or missing fuel filler cap · easy
- Leak in the evaporative system · moderate
- Faulty EVAP leak detection pump · moderate
Less common
- Blocked or pinched vent hose · easy
- Saturated charcoal canister · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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