Check Engine Light Code P0455 | O'Reilly Auto Parts

Skip to content

Diagnostic trouble code P0455 refers to a “Large Evaporative Emissions System Leak Detected”. The evaporative emissions, or EVAP, system in your vehicle is designed to trap fuel vapors in a closed system to prevent them from venting to the outside air. The fuel vapors are later introduced into the combustion chamber of the engine to be burned, increasing and maintaining performance and fuel efficiency. A large EVAP system leak means that fuel vapors are escaping from somewhere in the system, which can lead to poor fuel efficiency and pollution.

Issues related to a P0455 code can often include:

Fuel cap
Fuel tank filler neck
EVAP system hose
Fuel tank sending unit gaskets or seals
Carbon canister
Evaporative vent
Evaporative purge valve
Fuel tank
Fuel tank pressure sensor

The necessary parts and tools to clear this Diagnostic Trouble Code (DTC) might differ depending on your vehicle's make and model. If your Check Engine light is illuminated, stop by any O’Reilly Auto Parts and get an O’Reilly VeriScan® for your car, truck, or SUV and get a detailed VeriScan report with more information about your vehicle’s Diagnostic Trouble Code(s), along with possible causes and repair solutions. If you aren’t comfortable making these repairs yourself, our parts professionals can recommend a local shop to make your repair.

Show More Show Less

OBD-II fault code P0455 means a leak has been detected in your evaporative system, and refers to a large leak in the evaporative emission system. A small leak would instead be indicated by code P0456. Code P0455 means that your EVAP system doesn’t have adequate vacuum pressure and may be venting fuel vapors outside of the system.

P0455 Code Diagnosis

When you experience a P0455 diagnostic trouble code, your vehicle may be experiencing failure in one of a few areas:

Fuel cap
Fuel tank filler neck
EVAP system hose
Fuel tank sending unit gaskets or seals
Carbon canister
Evaporative vent
Evaporative purge valve
Fuel tank
Fuel tank pressure sensor

P0455 OBD-II Code Symptoms

Aside from a Check Engine light, the only other symptom you may notice is the smell of gasoline vapors.

Symptoms of a P0455 Code can include:

Check Engine light
Smell of gasoline

If you’re comfortable diagnosing the issue yourself or have other codes related to EVAP system problems, you may be able to determine the cause of your P0455 code with a physical inspection. It’s a good idea to start by checking or replacing your gas cap, since that could be the issue, but it’s possible that the problem may be elsewhere in the fuel system and require professional diagnosis.

What does DTC mean?

DTCs, or Diagnostic Trouble Codes, are generated by data collected by your vehicle’s onboard diagnostics system, or OBD system, and trigger your Check Engine light by identifying problems with one or more of your vehicle systems. DTC codes help explain what the issue is and where it is located.

Learn more about DTC codes

Show More Show Less

What are the most common DTCs?

Some of the most common DTCs include:

P0300-Random or Multiple Cylinder Misfire Code
P0301 through P0308- Single-Cylinder Misfire Codes
P0446- Evaporative Emissions Control System Codes
P0455- Evaporative Emissions Control System Codes-Leaks
P0420 or P0430- Catalyst Efficiency Codes
P0141- Oxygen (O2) Sensor Codes
P0171 or P0174- Lean Code
C0221- Wheel Speed Sensor

Show More Show Less

Can I clear DTCs?

To clear DTCs, you can use an OBD-II code reader to scan and clear the codes. However, this will only temporarily turn off your Check Engine light. If the problem is bigger than a code or sensor reset, the Check Engine light will likely reactivate.

Show More Show Less

If your Check Engine light is on, stop by any O’Reilly Auto Parts location where our Parts Professionals can scan and diagnose your illuminated Check Engine light for free with our exclusive O’Reilly VeriScan code reading service. An O’Reilly VeriScan provides a detailed report of possible causes and solutions or repairs for your illuminated Check Engine light. The O'Reilly VeriScan report, along with the O’Reilly Auto Parts How-To resources can help you understand what parts, tools, and services you need to clear your DTCs and Check Engine lights. If you aren’t comfortable performing any necessary repairs yourself, we are also happy to recommend a local repair shop.