Consequences of Ignoring the P1456 Error Code

Increased Emissions and Environmental Impact

• Uncontained EVAP system leaks allow more hydrocarbon vapor to escape into the atmosphere
• This contributes to air pollution and health hazards
• Failed state emission tests may leads to fines or inability to renew the vehicle registration

Progressive Drivability Problems and Loss of Performance

• Initial minor stalling, rough idling, and poor acceleration
• Gradually worsens to cause engine misfires, power loss, and stalling at high speeds
• Suboptimal air-fuel ratios and incorrect combustion may reduces the mileage
• Eventually, this may leads to no start conditions

Possible Failures in Other EVAP Components

• Sustained pressure fluctuations can damage the charcoal canister
• Liquid that enters the fuel EVAP system could corrodes the valves and sensors
• Strain on purge valve motor and vent valve solenoid could leads to failure
• Faulty oxygen sensors may receives contaminated readings
• Upstream engine components like the catalytic converter can get affected
• Replacing the entire EVAP system becomes necessary, which could be far more expensive

Preventing P1456 Codes

Regularly Checking the Gas Cap and the EVAP Hoses

• Visually inspect the gas cap seal and the EVAP hoses in a monthly basis
• Replace any cracked/damaged caps and hoses
• Ensure that the cap clicks tightly into the fuel filler neck
• Confirm that the hoses are securely attached at the both ends
• Check for any leaks, kinks and blockages after repairs or off-roading

Following the Fuel Cap Tightening Procedure

• When putting on the fuel cap, you should first turn it clockwise until there is an audible click. Which indicates that the vent holes on the cap have lined up properly. 

• Then, continue turning clockwise until a second click signals that a tight seal has been achieved between the cap and the filler neck. 

• You should then follow the fuel cap specifications for your specific model’s cap regarding how much further to tighten.

• Often this will be 1/4 to 1/2 a turn past the second click – and finally, check that the alignment arrows imprinted on the fuel cap line up with those imprinted on the filler neck.

Keeping the Charcoal Canister and Valves Clear of Debris

• To prevent debris buildup that could clog the charcoal canister and the valves, the canister exterior should be wiped down before any wet weather seasons.

•  When the debris is more likely, one should check that the protective filter screens located on the various ports of the canister and valves are clear of obstructions. 

• The electrical connections leading to the purge and the vent valves should be inspected.

• Low-pressure compressed air can be used to ensure to check that the valves are not sticking.

• Charcoal pellets that have become overly saturated with fuel vapor should be replaced; and a final check should be done to confirm the valves are sealing properly once the maintenance cleaning has been completed.