P2404
Evaporative Emission System Leak Detection Pump Sense Circuit Range/Performance
- Severity
- Low
- Driving
- No driving restriction
The leak detection pump's sense circuit is producing a signal within its valid range that does not match what the module expects while the pump runs. The circuit is intact; what it reports is not believable. That points at a mechanical problem in the pump or its plumbing at least as often as an electrical one.
Possible causes
- CommonCorroded or water-damaged connector at the pump
- CommonFailed sense switch or sensor inside the pump assembly
- CommonDamaged wiring on the underbody run
- PossiblePoor earth at the pump
- PossibleBlocked or kinked vapour line preventing the pump from building pressure
What you might notice
- Check engine light on
- Failed emissions test
- Occasionally a smell of fuel
- Usually nothing else - EVAP faults rarely affect how the car drives
What to check, in order
- Inspect the connector and its wiring before condemning the component. Everything in this system lives under the vehicle in the path of road salt and spray, and a corroded connector produces these codes far more often than a failed part does.
- Watch the sense signal on live data while commanding the pump. It should change state as the pump runs; one that never moves is the sense circuit, one that moves erratically is usually a connection.
- Check the vapour lines for kinks and blockages. A pump that cannot build pressure because the line is blocked reports the same thing as a failed sensor.
- Check the earth before replacing the pump assembly. These are usually sold as a complete unit and are not cheap.
- Check the fuel filler cap and the EVAP system for leaks before assuming the pump is at fault. A pump that cannot reach test pressure because the system genuinely leaks is working correctly and reporting the truth.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx