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P0455: Major Leak in Evaporative Emission System

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    This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.
    edited by
    Director, Editorial Content
    Steven Ewing has worked in the automotive industry since 2003. In that time, he's written thousands of car-related articles and tested just as many vehicles. Steven is Edmunds' director of editorial content and has previously been on staff at Winding Road magazine, Autoblog, Motor1.com, CNET Roadshow, and was the U.S. correspondent for Top Gear magazine. Steven has also contributed to Automobile magazine, Ars Technica, Car and Driver, The Drive, Jalopnik, SlashGear, and dozens of other publications. In his spare time, Steven loves to play the drums, cook, and lust over small JDM cars that never made it to the States.

Understanding error code P0455

Error code P0455 is an OBD-II diagnostic trouble code that signifies a major leak detected in the evaporative emission control (EVAP) system. This system is designed to prevent gasoline vapors from escaping into the atmosphere, and the diagnostic code appears when the vehicle's onboard computer detects a leak in the EVAP system that is equivalent to a hole 0.04 inch in diameter or larger.

The importance of resolving P0455

Addressing a P0455 error code is crucial because it involves the vehicle's evaporative emission control system, which plays a significant role in reducing harmful emissions. Ignoring this issue can not only lead to an increase in emissions but can potentially result in the vehicle failing emissions testing that's required in many regions. And it may indicate a fuel vapor leak, which poses a safety risk.

Driving with error code P0455

A P0455 error code might not create any immediate drivability issues, but driving with this problem can lead to a reduction in fuel efficiency. More importantly, it poses environmental and safety risks due to the potential for fuel vapors to escape.

Common symptoms of a P0455 error code

  • Check engine light is illuminated on the dashboard
  • Fuel odor due to evaporating gasoline vapors
  • Difficulty starting the engine or a rough idle (less common)
  • Failed emissions test due to excessive hydrocarbon emissions

Diagnosing the P0455 error code

Diagnosing a P0455 error involves several steps to locate the source of the leak within the EVAP system. A mechanic will inspect the gas cap for damage or improper sealing since this is a common culprit. After this inspection, the mechanic might use a machine to fill the EVAP system with smoke and then inspect for smoke escaping from leaks. Advanced diagnostic tools can also be used to check the operation of the EVAP system components, such as the purge valve and the vent valve.

Repairing the P0455 error code

Repairing a P0455 code depends on the source of the leak. Common repairs include:

  • Replacing or tightening the gas cap if it's found to be faulty or loose
  • Replacing damaged or cracked EVAP hoses or components
  • Repairing or replacing the purge valve or vent valve if either fails diagnostics
  • Sealing or replacing the EVAP canister if it's leaking

Each repair aims to restore the integrity of the EVAP system to prevent vapor leaks and ensure the system functions as designed, reducing emissions and improving vehicle safety.

Edmunds.comby

This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.

Steven Ewingedited by

Steven Ewing has worked in the automotive industry since 2003. In that time, he's written thousands of car-related articles and tested just as many vehicles. Steven is Edmunds' director of editorial content and has previously been on staff at Winding Road magazine, Autoblog, Motor1.com, CNET Roadshow, and was the U.S. correspondent for Top Gear magazine. Steven has also contributed to Automobile magazine, Ars Technica, Car and Driver, The Drive, Jalopnik, SlashGear, and dozens of other publications. In his spare time, Steven loves to play the drums, cook, and lust over small JDM cars that never made it to the States.

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