What does P0456 Evaporative Emissions System - Small leak detected mean?
The P0456 code refers to a small leak detected in the Evaporative Emissions System of a vehicle.
This system is responsible for preventing fuel tank vapors from venting into the atmosphere and instead purges them into the engine to be burned.
The Powertrain Control Module (PCM) performs various tests on the EVAP system and when it detects a small leak, the code is set.
This code is often caused by a faulty gas cap or a small leak in the EVAP hoses, fuel tank hoses, purge valve, vent valve, or EVAP canister.
To diagnose the issue, a scan tool can be used to activate the vent solenoid and monitor the fuel tank pressure.
If a leak is found, a smoke machine can help locate the faulty component.
P0456 Symptoms
- Malfunction Indicator Lamp (MIL) may be illuminated
Possible P0456 Causes
- Incorrect or faulty gas cap
- Filling the fuel tank with the engine running
- Improperly tightened gas cap
- Small leak in EVAP hoses or fuel tank hoses
- Small leak in purge valve or vent valve
- Leaking EVAP canister
Troubleshooting P0456 error code
- Use a scan tool to activate the vent solenoid and monitor the fuel tank pressure sensor
- If the system is sealing properly, the fuel tank pressure will stay consistent
- If the system is not sealing properly, use a smoke machine to locate the faulty component
- Do not pressurize the EVAP system with air pressure
