PO455 Technical Description
Evaporative Emission Control System Leak Detected (gross leak)
In this guide, you’ll learn what the PO455 trouble code means, its symptoms, causes, and how to fix it. You’re likely here because your car is showing this code and you want a solution.
I’ve tackled this issue plenty of times before and know what works.
By the end of this article, you’ll have clear steps to identify and fix the PO455 code, ensuring your car runs smoothly again.
Let’s get right into it.
Key Takeaways
- PO455 indicates a large leak in the EVAP system.
- Common symptoms include a Check Engine Light and fuel smell.
- Causes often include a loose gas cap or faulty EVAP components.
- Diagnose by inspecting the gas cap, hoses, purge valve, vent valve, and charcoal canister.
- Use a smoke test to find hard-to-spot leaks.
- Prompt repair is essential for emissions and fuel efficiency.
Table of ContentsShow
What Does PO455 Trouble Code Mean?
The PO455 trouble code indicates that your vehicle’s onboard diagnostics system has detected a large leak in the Evaporative Emission Control (EVAP) system.
This system captures fuel vapors from the fuel tank and prevents them from escaping into the atmosphere.
The code is triggered when the system detects a significant leak or a failure to maintain the proper vacuum.
The EVAP system is crucial for reducing emissions and improving fuel efficiency. When there’s a large leak, fuel vapors escape into the air, causing your vehicle to fail emissions tests and potentially leading to environmental harm.
Several components make up the EVAP system, including the gas cap, purge valve, vent valve, charcoal canister, and various hoses. The PO455 code often means that there is a problem with one or more of these components.
Addressing the PO455 trouble code promptly is essential to maintain your vehicle’s performance and pass emissions tests.
If left unchecked, it can lead to decreased fuel efficiency and more significant repair costs down the road.
PO455 Trouble Code Symptoms
When your vehicle has a PO455 trouble code, you’ll notice several signs. Here are the most common symptoms:
- Check Engine Light on
- Noticeable fuel smell around the vehicle
- Decreased fuel efficiency
- Difficulty starting the engine
PO455 Trouble Code Causes
Several issues can cause the PO455 trouble code. Here are the most common causes:
- Loose or faulty gas cap
- Cracked or disconnected EVAP hoses
- Faulty purge valve
- Faulty vent valve
- Leaking charcoal canister
- Damaged fuel tank
How To Fix A PO455 Trouble Code
A PO455 trouble code indicates a “Large Leak Detected in the Evaporative Emission Control System (EVAP).” This can often be related to a faulty gas cap, leaks in the EVAP hoses, or issues with the purge or vent solenoid. Below are steps for diagnosing and repairing this code:
1. Visual Inspection
Start with a visual inspection of the gas cap to ensure it is not loose, cracked, or otherwise faulty. If the cap appears damaged or worn, replace it and reset the code to see if it returns.
2. Check EVAP System Hoses
Inspect all EVAP system hoses for cuts, cracks, or disconnections. This includes checking hoses that connect to the purge valve, vent valve, and the charcoal canister.
3. Smoke Test
To identify hard-to-find leaks, perform a smoke test. This involves injecting smoke into the EVAP system and watching for where smoke escapes. Any smoke leaking out indicates the presence of a leak.
4. Inspect Purge and Vent Valves
Test the operation of the purge valve and the vent valve. Both should have the ability to open and close properly. You can test these with a hand-held vacuum pump to ensure they are sealing completely when closed.
5. Replace Faulty Components
Any damaged hoses, seals, or connections identified during the diagnosis should be replaced. This also applies to the gas cap, purge valve, or vent valve if they are found to be faulty.
6. Tighten Connections
Ensure all hose connections, including those at the purge and vent valves and the charcoal canister, are secure and tight.
7. Clear the Code
After repairs are made, clear the diagnostic trouble code with an OBD-II scanner. Then, drive the vehicle to see if the code returns.
8. Perform a Follow-Up Test
If the code does not return, perform another smoke test to confirm that all leaks have been successfully repaired.
Regularly checking the components of the EVAP system as part of routine maintenance can prevent issues related to the PO455 code. Make sure the gas cap is always securely tightened after refueling and periodically inspect EVAP system components for signs of wear or damage.
Conclusion
Now you know what the PO455 trouble code means and how to fix it. Ready to tackle it yourself?
Have you had any luck fixing a PO455 code before?
Drop a comment below with your experience or any questions you have!
