P0440 - EVAP System
P0440 is a generic powertrain diagnostic trouble code indicating EVAP System. It relates to the Auxiliary Emission Controls system.
DTC Breakdown (SAE J2012)
| System | Powertrain (P) |
| Type | Generic |
| Subsystem | Auxiliary Emission Controls |
| Fault Index | 40 |
| Standard | SAE J2012 / ISO 15031-6 |
What does diagnostic code P0440 mean?
The engine control module logged P0440 after detecting a general malfunction in the Evaporative Emission Control (EVAP) system's ability to seal and hold vacuum. This is a generic code often accompanied by more specific leak codes.
Severity Level & Driveability Details
Severity: Low
This fault has zero effect on engine driveability or mechanical safety.
Common Symptoms of P0440
- Check engine light illuminated.
- Occasional faint gasoline vapor smell around the vehicle.
- No noticeable impact on engine performance.
Typical Causes for P0440
- Loose, incorrectly tightened, or damaged gas cap gasket.
- Small cracks or splits in the EVAP canister vacuum hoses.
- Leaking fuel tank filler neck seal or sending unit seal.
- Defective EVAP purge or vent control solenoid.
Diagnostic and Troubleshooting Steps
To diagnose the EVAP system, a technician will check the gas cap first. If it is fine, they will perform a smoke test, introducing diagnostic smoke into the EVAP lines to locate the leak path.
Typical Repairs and Fixes
- Tightening, cleaning, or replacing the gas cap.
- Replacing damaged or cracked EVAP vacuum lines.
- Replacing the EVAP purge or vent valve solenoid.
Sensor Location & Parts Involved
The EVAP canister and vent valve are located underneath the vehicle near the fuel tank; the purge valve is in the engine bay.
Clearing Code & Recurrence
Clear the code with a scan tool to reset the monitors and perform a verification drive.
Emissions & Smog Inspection Impact
Allows raw fuel vapors (hydrocarbons) to vent into the atmosphere, causing smog check failures.
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Related Diagnostic Codes
Sources & References
This diagnostic guide is compiled and verified against the following authority sources:
- EPA EVAP Standards
- CARB OBD II regulations
Frequently Asked Questions about P0440
What does the EVAP control system malfunction code P0440 mean?
The engine control module logged P0440 after detecting a general malfunction in the Evaporative Emission Control (EVAP) system's ability to seal and hold vacuum. This is a generic code often accompanied by more specific leak codes.
Is it safe to drive with the EVAP control system malfunction code P0440 active?
Yes, an EVAP fault poses no danger to vehicle function.
How much does it cost to repair a EVAP control system malfunction code P0440 fault?
A new gas cap is $15-$30, while vent or purge solenoids run $150-$300 and carbon canisters cost $300-$500.
What are the common causes of the EVAP control system malfunction code P0440?
Trigger conditions for the EVAP control system malfunction code P0440 include: Loose, incorrectly tightened, or damaged gas cap gasket., Small cracks or splits in the EVAP canister vacuum hoses., Leaking fuel tank filler neck seal or sending unit seal..
Can I clear the check engine light for EVAP control system malfunction code P0440?
Clear the code with a scan tool to reset the monitors and perform a verification drive.
Will the EVAP control system malfunction code P0440 cause an inspection failure?
Allows raw fuel vapors (hydrocarbons) to vent into the atmosphere, causing smog check failures.