Code status
Needs verification
Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.
- System
- Emissions
- Scope
- iso-sae-controlled-p0
- Standard
- SAE J2012 / ISO 15031-6
- Source
- legacy-import
Diagnostic boundary
A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.
Do not stop at the gas cap if the code returns; P0440 can come from many EVAP plumbing, valve, wiring, or sealing faults.
Useful checks before replacing parts
- Check fuel cap sealing where applicable, EVAP hose routing, purge valve behavior, vent valve operation, and tank-area connections.
- Use smoke testing or the vehicle-specific EVAP test routine when a visual inspection does not find the fault.
- Review related EVAP codes because they often narrow the fault to leak size, purge flow, or vent control.
Related OBD-II codes
These nearby emissions entries can help compare wording and fault area. They may share the same verification status as the source database.