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P0455 OBD-II Evaporative Emission System Leak Detected (Large Leak) Trouble Code




The P0455 OBD-II trouble code stands for Evaporative Emission System Leak Detected (large leak) which means that the Evaporative Emission Control (EVAP) system is leaking and can’t keep pressure. This code can happen for many reasons and is often associated with the P0440 trouble code.

In this article, I will be talking about the P0455 trouble code, its symptoms, causes, and how to fix it.

What Does The P0455 Code Mean?

P0455 OBD-II Evaporative Emission System Leak Detected (Large Leak) Trouble Code

The P0455 trouble code means that the car’s software has found a large (gross) leak in the evaporative emissions system and made a note of it. Simply put, this DTC means that the vehicle’s EVAP system has been broken in some way, which lets fuel vapor escape into the air.

Modern cars have built-in evaporative emissions systems to catch the fuel vapor that naturally escapes. The vapors are then put in an EVAP canister and sent back into the engine through a purge valve and hoses.

These fuel vapors are then burned during combustion rather than released into the atmosphere.

The P0455 trouble code means that there is a leak in this system, which means that fuel vapors can’t be caught and stored as intended. This leak is detected by abnormal readings from an onboard pressure sensor, which are then interpreted by the vehicle’s ECM/PCM.

When these pressure readings differ, an active fault code is stored and the vehicle’s check engine light illuminates.

(See also: P0327 OBD-II Knock Sensor 1 Circuit Low Bank 1 or Single Sensor Trouble Code)

Which Models Are Affected By The P0455 Code

MakeAffected By P0455 Code

What Are The Possible Causes of the P0455 Code?

The P0455 code is caused when the vehicle’s computer detects a large leak in the emissions evaporative system.

Though the exact cause of The P0455 trouble code varies from case to case, almost every instance of this fault is caused by a leak in the evaporative emissions system.

Some of the most common causes of diagnostic trouble code P0455 are:

  • The gas cap is missing, left open, or improperly secured.
  • The gas cap is defective or damaged.
  • The fuel tank filler neck is deformed.
  • The fuel tank has a crack or is defective.
  • The fuel tank pressure sensor is defective.
  • The canister of charcoal EVAP is cracked or damaged.
  • The EVAP hoses and clamps are disconnected, cracked, or punctured.
  • The EVAP vent solenoid is defective or stuck open.
  • The EVAP purge valve is defective and stuck open.

(See also: P0131 OBD-II O2 Sensor Circuit Low Voltage Bank 1 Sensor 1 Trouble Code)

What Are The Common Symptoms of The P0455 Code?

Because trouble code P0455 is strictly emissions-related, your vehicle is unlikely to exhibit any additional symptoms other than the appearance of a check engine light. This is because, in a true operational sense, a vehicle’s evaporative emissions system has little to do with an engine function.

Here are the most common symptoms of the P0455 trouble code:

  • The Check Engine Light is illuminated.
  • A slight reduction in fuel economy.
  • The odor of gasoline.

Is It Safe To Drive With a P0455 Code?

Yes, driving with a P0455 code is safe because it does not affect how the vehicle performs. However, driving with an emissions leak might lead to decreased fuel economy or even a rough idle.

In most cases, diagnostic trouble code P0455 is not a serious problem, but it should be investigated further. This fault is unlikely to cause any drivability issues and poses no risk of further vehicle damage.

(See also: P0107 OBD-II Manifold Absolute Pressure/Barometric Pressure Circuit Low Trouble Code)

How To Diagnose The P0455 Code

To diagnose the P0455 trouble code, you should:

  1. Use an OBD-II scanner to diagnose this issue.
  2. Check the gas cap to ensure it is securely closed and there are no gaps or signs of leakage.
  3. Inspect the entire fuel system for any vacuum leaks.
  4. Check the hoses and connections for the evaporative emission control system for any cracks, kinks, or loose connections.
  5. Inspect the purge and vent solenoids for any signs of damage or contamination.
  6. Check the fuel tank pressure sensor for any signs of damage.
  7. Test the fuel tank pressure for any indications of a leak or faulty pressure regulator.
  8. Check the integrity of the charcoal canister for any signs of damage or contamination.

Most Common Mistakes When Diagnosing The P0455 Code

Diagnostic errors are mostly caused by failing to follow the procedure. The procedure is both logical and economically sound way to proceed. A fuel cap is usually less than $30, but other components, such as the Evaporative Emission System purge valve, can cost hundreds of dollars.

How Much Does It Cost To Repair P0455 Code

Diagnosing P0455 can cost up to $100.

Replacing the gas cap costs around $25.

Replacing the vent valve or purge solenoid costs $200 – $300.

Charcoal canister repair, if needed costs: $350 – $600.

Filler neck replacement costs between $300 – $440.

MakeP0455 CodeRepair Cost
ToyotaYes$25 – $600
NissanYes$25 – $600
ChevroletYes$25 – $600
BMWYes$25 – $600
AudiYes$25 – $600
BuickYes$25 – $600
MercedesYes$25 – $600
GMCYes$25 – $600
SuzukiYes$25 – $600
TataYes$25 – $600
LexusYes$25 – $600
MazdaYes$25 – $600
MitsubishiYes$25 – $600
KiaYes$25 – $600
JeepYes$25 – $600
FiatYes$25 – $600
HondaYes$25 – $600
HyundaiYes$25 – $600
OpelYes$25 – $600
FordYes$25 – $600
FiatYes$25 – $600
PeugeotYes$25 – $600

What Repairs Can Fix The P0455 Code?

Repairs that can fix the P0455 trouble code include the following:

  • Replace the gas cap, if it doesn’t tighten or seal.
  • Replace the fuel filler neck if it is damaged or has anything that prevents it from sealing with the cap.
  • Repairing any hose issues.

How To Fix The P0455 Code

To fix the P0455 trouble code, you need to:

  • Replace the gas cap, if it is necessary
  • Inspect the EVAP system for any signs of tampering or damage.
  • Check for any loose or disconnected hoses or connectors in the EVAP system.
  • Inspect the EVAP canister for any signs of damage or clogging.
  • Examine the EVAP system for any vacuum leaks.
  • Inspect the purge valve for any signs of damage or clogging.
  • Replace any faulty or worn-out components in the EVAP system.
  • Clear the trouble code and retest the system.

In Conclusion

The P0455 trouble code is a common code that indicates a problem with the evaporative emission control system. This system is responsible for controlling the release of fuel vapors from the vehicle, and when it is not functioning properly, it can cause the engine to run at lower efficiency and potentially cause damage to the catalytic converter.

This code should be addressed immediately to avoid further damage to the vehicle and to ensure proper engine performance. Diagnostic testing should be performed to determine the exact cause of the code and the necessary repairs should be done as soon as possible. Professional help should be sought if the problem is not resolved quickly and easily.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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