P0455 Code Symptoms, Causes (& Repair Cost 2022)

The evaporative emission control (EVAP) system prevents fuel vapors from escaping into the atmosphere. The fuel vapors from the fuel tank are absorbed and stored by charcoal pellets in the charcoal canister. P0455 is a diagnostic trouble code that indicates a large fuel vapor leak or lack of purge flow in the EVAP control system. This can happen for multiple reasons, and you need to diagnose the specific cause for this code to be triggered in your situation. This article explains the P0455 code symptoms and causes.

What the P0455 code means

Diagnostic trouble code (DTC) P0455 indicates that your car’s PCM detects a large leak in your Evaporative Emission (EVAP) Control System.

P0455 code

Today’s vehicles utilize integrated evaporative emissions systems to capture the natural dissipation of fuel vapor. These vapors are then stored in an EVAP canister before being reintroduced into an engine’s intake through a purge valve and accompanying hoses.

From this point, these fuel vapors are burnt during combustion rather than being allowed to escape into the atmosphere.

The P0455 code indicates a leak within this system, making it impossible to capture and retain fuel vapors as intended. This leak is registered by abnormal readings captured by an onboard pressure sensor and interpreted by the vehicle’s ECM/PCM.

When discrepancies in these pressure readings develop, an active fault code is stored, and a vehicle’s check engine light is illuminated.

Causes of the P0455 Code

The following are the most common causes of P0455 code:

  • Faulty or damaged gas cap
  • The gas cap is missing, left open, or not secured properly
  • Faulty system pressure sensor
  • Damaged gas tank fuel filler neck
  • EVAP vent solenoid is faulty or stuck open
  • Cracked fuel tank
  • Defective vent valve solenoid
  • Faulty EVAP purge valve
  • Damaged or cracked charcoal EVAP canister
  • Cracks, holes, or splits in EVAP hoses
  • Faulty PCM

Read More: Causes and Symptoms of P0453 

Symptoms of the P0455 Code

Due to the fact that trouble code P0455 is strictly emissions-based in nature, your vehicle is highly unlikely to exhibit any additional symptoms outside of the appearance of a check engine light.

Following are the symptoms of the P0455 code:

  1. Illuminated check engine light
  2. A noticeable gasoline fuel smell in the filler area or tank area.
  3. It is also possible the smell could also come from the evaporative lines in the engine intake system.

Read More: Symptoms and Causes of P0451

Common P0455 Code diagnostic mistakes

Diagnostic errors are largely due to not following the procedure. The process is a logical and economically sound way to proceed. If you need a fuel cap, they are usually less than $20, but other components, such as the Evaporative Emission System purge valve, can cost several hundred dollars.

How to Fix the P0455 Code

The following steps will assist you in diagnosing and repairing the root cause of your vehicle’s P0455 fault code.

1) Scan for Additional Codes

Before beginning the diagnostic process of the P0455 code, it is important to check for the presence of any additional DTCs. Thoroughly diagnose any fault codes that are found.

2) Check Gas Cap

A loose or damaged gas cap is, by far, the most common cause of fault code P0455. Therefore, thoroughly inspecting your vehicle’s gas cap is an excellent place to start the diagnostic process.

Check to ensure that your vehicle’s gas cap is tight and free of visual defects. Next, clear code P0455 with a suitable OBD-II scanner before taking a brief test drive.

3) Replace Gas Cap if needed

If the P0455 code persists, replace your gas cap with a cap of OEM equivalency. Again, clear all active fault codes and repeat your test drive.

4) Inspect Hoses and Filler Neck

If DTC P0455 returns, you should now inspect all related hoses for signs of deterioration. The presence of obvious defects will warrant replacement. The vehicle’s EVAP canister and fuel tank filler neck should also be inspected in a similar manner.

5) Smoke Test

If the source of your vehicle’s P0455 DTC has yet to be uncovered, a smoke test can be used to uncover any underlying leaks. A shop-grade smoke machine can be plumbed directly into the vehicle’s EVAP system, at which point smoke will escape from even the smallest of leaks.

6) Run System Functionality Tests

If there is no leak, a system functionality test should be conducted with the use of a bi-directional scan tool. Such tests will typically reveal the presence of a faulty purge valve or solenoid.

The system’s pressure sensor is likely compromised if all appears to be functioning correctly. This can be verified through testing with a multimeter, in accordance with factory service literature.

How serious is the P0455 code?

In most cases, diagnostic trouble code P0455 is not considered a serious issue yet warrants further attention. This fault is unlikely to pose any drivability-related difficulties and presents no danger of further vehicle damage.

System leak failure can cause excessive fuel consumption in certain circumstances, so it is best to take your vehicle to a technician at your first opportunity.

However, it is important to understand that P0455 is an emissions code and can cause hardship when attempting to reach compliance in states where regular emissions testing is required. Tests of this nature often involve scanning a vehicle’s OBD-II system for active emissions codes. A favorable outcome is unlikely if active codes of this nature are uncovered.

What repairs can fix the P0455 code?

The following repairs can fix the P0455 code:

  • Replacing the gas cap if it doesn’t tighten or seal
  • Replacing the fuel filler neck if it’s damaged or has anything that would prevent it from sealing with the cap
  • Repairing any hose problems
  • Repairing damaged wiring and connections
  • Replacing faulty system pressure sensor
  • Repairing or replacing the cracked fuel tank
  • Repairing or replacing the bad vent valve solenoid

Po455 Code Repair Cost

For each possible repair, the estimated cost includes the cost of the relevant parts and the labor required to make the repair. The following table shows the repair cost of the P0455 code according to the repair of each part:

EVAP Line$20 to $115
Gas Cap$12 to $75
Purge Volume Control Valve$150 to $230
EVAP Vent Control Valve $130 to $220

FAQ Section

Can you drive with code P0455?

You may drive your vehicle while trouble code P0455 is present unless the gas vapor odors are very strong or you see obvious fuel (liquid) leaks. Extreme danger, seek repairs if either of these two scenarios exists. Note that a large fuel vapor leak may cause fuel economy issues.

Can I drive with an EVAP leak?

Yes, you are still safe to drive. The EVAP (Evaporated Emission Control System) is used to prevent gasoline vapors from escaping into the air from the fuel tank system to control greenhouse emissions.

How easy is it to diagnose a P0455 Code?

To diagnose a leak, a technician will use an OBD-II scanner. They should record all store codes and the associate freeze frame data, reset the code and take the vehicle for a test drive to see whether the code reappears. A complete drive cycle must be completed.

To perform this test, most vehicles need the fuel level to be between 15% and 85%. If the fault code returns, the mechanic needs to inspect your vehicle and search for the location of the leak.

If they can’t find any obvious leaks, they’ll use a smoke test to look for them. A smoke test is a series of tests your mechanic will perform to look for leaks in any vacuum hoses. The test can determine if any routing in the vacuum system has a leak. The problem might be the sensor if there isn’t a noticeable leak. In this case, the sensor needs to be tested by the manufacturer’s instructions.

What would cause a large EVAP leak?

A common cause is a missing or loose gas cap. This easy-to-fix solution could be all you need to restore your EVAP system. However, minor tears or rotten spots in your EVAP hose could also be the culprit. Your filter canister may also be cracked.

Can an exhaust leak cause a P0455 code?

The P0455 code indicates a leak within this system, making it impossible to capture and retain fuel vapors as intended.

What are the symptoms of a bad leak detection pump?

The check engine light or the malfunction indicator light turns on if there’s an issue with the Leak Detection Pump. A diagnostic trouble code should register in the vehicle’s memory because of a poorly working pump.

Can a large EVAP leak cause a misfire?

The cause could be anything from a hard to find vacuum leak to dirty fuel injectors, low fuel pressure, a weak ignition coil, or compression problems. A leaking EGR valve can cause a random misfire and act like a vacuum leak.

How long does it take to fix the EVAP leak?

According to the repair type, this process can take anywhere from a few minutes to several hours. Replacing the car gas cap is the easiest and cheapest fix for about $30, while locating an EVAP leak in either the vacuum feed lines or charcoal canister may be more difficult and run you upwards of $610.

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