P0456 - EVAP System Leak Detected (very small leak)
P0456 is a generic powertrain diagnostic trouble code indicating EVAP System Leak Detected (very small leak). It relates to the Auxiliary Emission Controls system.
DTC Breakdown (SAE J2012)
| System | Powertrain (P) |
| Type | Generic |
| Subsystem | Auxiliary Emission Controls |
| Fault Index | 56 |
| Standard | SAE J2012 / ISO 15031-6 |
What does diagnostic code P0456 mean?
The EVAP system has detected a very small fuel vapor leak, indicating a leak path as small as 0.02 inches.
Severity Level & Driveability Details
Severity: Low
It does not affect vehicle performance or safety.
Common Symptoms of P0456
- Check engine light illuminated due to a very small EVAP leak.
Typical Causes for P0456
- Minor leak in the gas cap seal.
- Hairline cracks in EVAP hoses.
- Leaking purge valve.
- Minor crack in the charcoal canister.
Diagnostic and Troubleshooting Steps
Perform a smoke test. A highly sensitive smoke machine is required to locate extremely small leaks.
Typical Repairs and Fixes
- Cleaning or replacing the gas cap.
- Replacing aged/cracked EVAP lines.
- Replacing the vent control 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 P0456
What does the EVAP control system very small leak code P0456 mean?
The Evaporative Emission Control (EVAP) system logged P0456 after detecting a very small leak in the sealed fuel vapor loop.
Is it safe to drive with the EVAP control system very small leak code P0456 active?
Yes, an EVAP fault poses no danger to vehicle function.
How much does it cost to repair a EVAP control system very small leak code P0456 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 very small leak code P0456?
Trigger conditions for the EVAP control system very small leak code P0456 include: Loose, dirty, or cracked gas cap seal., Hairline cracks in the EVAP canister or vacuum lines., Failed EVAP vent control valve or purge valve..
Can I clear the check engine light for EVAP control system very small leak code P0456?
Clear the code with a scan tool to reset the monitors and perform a verification drive.
Will the EVAP control system very small leak code P0456 cause an inspection failure?
Allows raw fuel vapors (hydrocarbons) to vent into the atmosphere, causing smog check failures.