P0455 on 2009-2016 Chevrolet Traverse: EVAP Large Leak Causes and Fixes

What's Unique About the 2009-2016 Chevrolet TRAVERSE

The first-generation Chevrolet Traverse, along with its GM Lambda platform mates (Buick Enclave, GMC Acadia, and Saturn Outlook), is known for EVAP system issues, particularly with the purge and vent valves on the 3.6L V6 engine. These components are common failure points that lead to P0455. In fact, General Motors has issued technical service bulletins (TSBs) that provide diagnostic advice for this specific code, acknowledging the frequency of the issue. While a loose gas cap is a universal cause, on this platform, the solenoid valves should be high on the suspect list if the gas cap is secure. 🎬 Watch: What to check for P0455 when the gas cap is fine. The purge valve, in particular, is a frequent culprit and is often associated with the companion code P0496.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• A faint smell of fuel, especially around the rear of the vehicle.
• Difficulty starting the engine right after refueling (often points to a stuck-open purge valve).
• Slightly rough or erratic idle (can be caused by a stuck-open purge valve creating a vacuum leak).
• Difficulty filling the fuel tank (nozzle clicks off repeatedly), which can point to a faulty or stuck-closed vent solenoid.

Most Likely Causes

1. Loose or Faulty Gas Cap 🔴 High Probability This is the most common cause for P0455 on any vehicle. The gas cap seal can degrade, crack, or stiffen over time, or the cap may not have been tightened correctly after refueling. Always ensure it clicks at least once.
   How to confirm: Ensure the gas cap is tightened until it clicks. Inspect the rubber O-ring seal on the cap for any cracks, stiffness, or visible damage. An old, worn seal is a very common failure point.
   Typical fix: Tighten or replace the gas cap.
   Est. part cost: $15-$30
2. Faulty EVAP Purge Valve/Solenoid 🔴 High Probability This is a very common failure item on the 3.6L V6 engine used in the Traverse and its platform mates. The valve can get stuck open, creating a constant vacuum leak into the intake manifold that the system interprets as a large leak. This is often the cause of hard starting after fill-ups.
   How to confirm: Remove the valve, which is located on the top rear of the engine under the plastic cover. With the valve disconnected, try to blow through the port that connects to the intake manifold. If air passes through when it is not energized, it has failed and is stuck open. You can also feel it clicking loudly or pulsating when the engine is running, which can be a sign of failure.
   Typical fix: Replace the EVAP purge valve. This is a simple DIY job requiring basic tools.
   Est. part cost: $25-$50
3. Faulty EVAP Vent Valve/Solenoid 🟡 Medium Probability This valve, located near the charcoal canister by the fuel tank, is exposed to road debris, moisture, and dust, causing it to fail. It can get stuck open, preventing the system from sealing properly for its self-test. GM has issued a TSB (23-NA-073) acknowledging that dust intrusion can plug this component.
   How to confirm: A scan tool can command the valve to close for testing. A definitive diagnosis often requires a smoke test to see if smoke escapes from the vent valve when it should be closed. Replacement is often the most practical test if a smoke machine isn't available.
   Typical fix: Replace the EVAP vent solenoid. Access is from underneath the vehicle.
   Est. part cost: $30-$60
4. Cracked or Disconnected EVAP Hoses ⚪ Low Probability Over time, the rubber and plastic hoses in the EVAP system can become brittle and crack, causing leaks. The connections at the purge valve or canister are common places to check.
   How to confirm: Visually inspect all accessible EVAP lines from the engine bay to the fuel tank area. The most reliable method is to have a professional smoke test performed, which will make any leaks, even small ones, visible as smoke exits the crack or loose connection.
   Typical fix: Replace the damaged section of hose or re-secure the connection.
   Est. part cost: $10-$40

Rare But Worth Checking

• Cracked Charcoal Canister: The plastic housing of the charcoal canister can crack from age or impact, creating a large leak. This is usually found during a smoke test when smoke is seen emitting from the canister body itself.
• Rusted Fuel Filler Neck: In areas with heavy road salt use (the 'Salt Belt'), the metal fuel filler neck can rust through, creating a leak that will trigger the P0455 code. A visual inspection of the neck (after removing the wheel well liner) will reveal significant corrosion or holes.
• Damaged wiring to Vent/Purge Solenoid: Less common, but the wiring harness leading to the vent solenoid, in particular, can be damaged due to its location under the vehicle, causing the valve to not function correctly.

Diagnosis Steps

1. Check the gas cap. Remove it, inspect the seal for damage, and reinstall it, ensuring it clicks several times. Clear the code and drive for a few days to see if it returns. This is the easiest and most common fix.
2. If the code returns, perform a visual inspection of the EVAP purge valve and its hoses in the engine bay. It is located on the back of the engine near the firewall, under the plastic engine cover.
3. Test the purge valve. With the engine off, remove the valve (one 10mm bolt and two connections). Try to blow through it from the canister side to the intake side. If air passes through, the valve is stuck open and must be replaced.
4. If the purge valve is good, visually inspect the EVAP vent solenoid and charcoal canister underneath the vehicle, near the spare tire and fuel tank, for any obvious cracks or damage.
5. Listen for symptoms. If you have trouble starting the car after getting gas, the purge valve is highly suspect. If you have trouble filling the tank without the pump clicking off, the vent solenoid is more likely the issue.
6. If no obvious issues are found, the most effective next step is a professional smoke test. A machine fills the EVAP system with a visible, often UV-dyed vapor, making it easy to pinpoint the exact location of any leak, no matter how small.

Parts You'll Likely Need

• Gas Cap (OEM #GT295 (ACDelco)) — This is the simplest and most common fix for a P0455 code. An old, worn, or loose cap will prevent the system from sealing.
  Trusted brands: ACDelco, Stant
  OEM price range: $20-$30
  Aftermarket price range: $15-$25
• EVAP Vapor Canister Purge Valve (OEM #12690512 (Supersedes 12610560)) — A very common failure point on this platform. It gets stuck open, causing a leak that the system detects. Often seen with code P0496 and causes hard starts after refueling.
  Trusted brands: ACDelco, Dorman (p/n 911-082), Standard Motor Products
  OEM price range: $35-$50
  Aftermarket price range: $25-$40
• EVAP Vapor Canister Vent Solenoid (OEM #214-2149 (ACDelco #25950499)) — Located near the fuel tank, this valve is exposed to the elements and frequently fails, getting stuck open and preventing the system from sealing.
  Trusted brands: ACDelco, Dorman
  OEM price range: $40-$60
  Aftermarket price range: $30-$50

Related Codes That Often Appear With This One

• P0442 — This code indicates a small EVAP leak. It can appear alongside P0455 if the system has multiple leaks or if a failing component is causing an intermittent leak size. GM TSB 21-NA-124 addresses both codes simultaneously.
• P0496 — This code indicates 'EVAP Flow During a Non-Purge Condition,' which almost always points directly to a faulty EVAP purge valve that is stuck open. If you see P0496 with P0455, the purge valve is the most likely culprit and should be the first part you test and replace.

Technical Service Bulletins (TSBs) & Recalls

• 21-NA-124: Diagnostic tips for MIL Illuminated with DTCs P0442 and/or P0455 Set.
• 23-NA-073: Evaporative DTCs P0442, P0446, P0455 or P0449, Caused by Dust Intrusion into the Evaporative Canister and Canister Vent Solenoid.

Platform-Specific Known Issues

• GM issued Technical Service Bulletin #21-NA-124 which provides diagnostic tips for technicians dealing with P0455 and P0442 codes, indicating this is a recognized issue on these vehicles.
• GM TSB #23-NA-073 notes that on vehicles operated in dusty environments, dust can enter the EVAP system and clog the canister and vent solenoid, causing codes like P0455.
• Some owners on forums have had to replace the purge valve multiple times, suggesting some aftermarket parts may have a high failure rate.

Mechanic-Grade Diagnostic Values

• EVAP Purge Valve/Solenoid Coil Resistance — expected: 15 to 30 Ohms. Failure: A reading far outside this range indicates a damaged internal circuit requiring valve replacement.
• EVAP Vent Valve/Solenoid Coil Resistance — expected: Approximately 14 to 16 Ohms. Failure: An open circuit (infinite resistance) or a reading significantly outside the expected range indicates a failed solenoid.
• Fuel Tank Pressure (FTP) Sensor Voltage — expected: Approximately 1.5V at rest (atmospheric pressure). Failure: Voltage less than 1.5V indicates positive pressure; voltage greater than 1.5V indicates vacuum. A sensor that does not change voltage when the system is sealed and purged/vented may be faulty.

Scan Tool Commands That Help

• GDS2 / Tech2 / Professional Scan Tool: EVAP Service Bay Test — This is an automated test that commands the vent valve to close and the purge valve to open, then monitors the Fuel Tank Pressure sensor to check if the system can build and hold a vacuum. A failure of this test confirms a leak or a non-responsive component.
• GDS2 / Tech2 / Professional Scan Tool: EVAP Purge/Seal — This function allows a technician to manually command the EVAP Vent Solenoid to close (seal the system) and then incrementally open the Purge Solenoid (from 0-100%) to create a vacuum. It is used to verify the function of both solenoids and the integrity of the system.

Wiring & Ground Locations

• EVAP Vent Solenoid Connector — On top of the fuel tank, part of the main fuel tank harness.. The wiring at this connector can become damaged or corroded, creating an open circuit (often triggering P0449) or preventing the vent valve from closing, which leads to a P0455 leak. On a 2013 Traverse, the wires are Red with a White tracer (12V+) and a solid White wire (solenoid control from ECM).

Real Owner Repair Stories

• Jeep Cherokee Forum (Jeep Cherokee (similar EVAP principle)) — P0455 Large EVAP Leak code.
  ❌ Tried (didn't work) Verified purge valve was working correctly.
  ✅ What actually fixed it The steel EVAP line running from the charcoal canister back to the fuel tank was badly rusted and rotted through, creating a large leak. The owner replaced the rusted steel section with polyethylene tubing to fix the issue. This is particularly relevant for vehicles in the 'Salt Belt'.
• Reddit user on r/AskMechanics (2012 Chevrolet Traverse LT 3.6L) — P0455 code, intermittent 'Tighten Gas Cap' message on dash.
  ❌ Tried (didn't work) Replaced vent canister purge solenoid (for a previous P0449 code)., Replaced gas cap with a new AC Delco part.
  ✅ What actually fixed it The user's post ended before a final resolution was confirmed, but the key takeaway is that replacing the gas cap and vent solenoid did not fix the P0455, pointing towards a more elusive leak in a hose, the canister, or the purge valve, which is a common next step. The user noted his wife frequently 'tops off' the fuel tank, a known cause of canister and solenoid failure.

OEM Part Supersession History

• 12610560 → 12690512, and later 12737252 — Standard part evolution by the manufacturer for improved reliability or manufacturing changes.
  Heads up: The newer part numbers are direct replacements for the older ones for the specified Traverse model years.
• 25932571 → 214-2149 (ACDelco part number) — This is the corresponding service part number from ACDelco for the original GM part.
  Heads up: 214-2149 is the correct service part for the vent solenoid on this platform.

Model Year Variations Within This Range

• 2009-2016: While the general EVAP system design is consistent, the vent solenoid is located on top of the fuel tank, which can make access more difficult than on other vehicles where it is mounted on the canister itself and easily accessible from underneath.