P0455 on 2007-2009 Saturn Aura: EVAP Gross Leak Causes and Fixes

What's Unique About the 2007-2009 Saturn Aura

The Saturn Aura from this period is a GM Epsilon platform vehicle, sharing many parts and systems with the Chevrolet Malibu and Pontiac G6. 🎬 Watch: A quick fix for the P0455 leak on this platform. As such, EVAP system issues and fixes are very similar across these models. A common point of failure on these GM vehicles is the EVAP purge solenoid located on the engine, which can get stuck open or closed. Another frequent issue is the vent solenoid located near the charcoal canister at the rear of the vehicle, which is exposed to road elements and can fail.

Symptoms You May Notice

• Check Engine Light is on
• A noticeable smell of gasoline, especially around the rear of the vehicle or after parking in a garage.
• Potentially a slight decrease in fuel economy.
• Difficulty starting the car immediately after refueling (if the purge valve is stuck open, causing a rich fuel mixture).
• Gas pump nozzle clicks off repeatedly when trying to refuel (if the vent valve is stuck closed, preventing air from escaping the tank).

Most Likely Causes

1. Loose, Damaged, or Incorrect Gas Cap 🔴 High Probability → Shop Fuel Tank Cap This is the most common cause for a P0455 code on any vehicle, as the cap can be left loose or its seal can degrade over time. Using a non-OEM cap can also lead to an improper seal.
   How to confirm: First, ensure the gas cap is tightened until it clicks several times. If the code returns, remove the cap and inspect the rubber O-ring or seal for cracks, stiffness, or damage. A brand new cap is a cheap and effective diagnostic step.
   Typical fix: Tighten the existing cap or replace it with a new OEM-spec gas cap. An ACDelco GT294 (GM Part #15846784) is a common replacement.
   Est. part cost: $15-$30
2. Failed EVAP Purge Solenoid (Purge Valve) 🟡 Medium Probability → Shop Vapor Canister This is a common failure point on many GM vehicles of this era, including the Aura and its platform mates. The valve, located on the engine, can get stuck open, creating a constant vacuum leak into the intake and often triggering a P0496 code alongside P0455.
   How to confirm: The purge solenoid is located on top of the engine. With the engine off, disconnect the valve and try to blow through it; it should be closed and not allow air to pass. A scan tool can be used to command the valve open and closed to check for an audible click and proper function.
   Typical fix: Replace the purge solenoid valve. The ACDelco part number is often 214-1680 🎬 Watch this step-by-step guide to replacing the purge solenoid. (GM #12597567).
   Est. part cost: $25-$60
3. Failed EVAP Vent Solenoid (Vent Valve) 🟡 Medium Probability → Shop Vapor Canister Located near the charcoal canister by the fuel tank, this component is exposed to road debris and moisture, leading to failure. If it gets stuck open, the EVAP system cannot seal to perform its pressure test. If it gets stuck closed, it can cause issues with refueling.
   How to confirm: The vent solenoid is normally open and should close when voltage is applied. A scan tool can command the valve closed for testing. A definitive diagnosis often requires a smoke test to see if smoke escapes from the vent valve when it's commanded shut.
   Typical fix: Replace the vent solenoid. The ACDelco part number is 214-2149 (supersedes GM #25932570). Dorman offers an alternative under part number 911-021.
   Est. part cost: $30-$90
4. Cracked or Disconnected EVAP Hoses ⚪ Low Probability Over time, rubber and plastic hoses can become brittle from heat and age, leading to cracks, especially at connection points. This is a common issue on aging vehicles.
   How to confirm: A visual inspection may reveal obvious cracks or disconnected lines. However, the most effective method is to have a professional smoke test performed. This involves injecting vaporized smoke into the EVAP system to see where it leaks out.
   Typical fix: Replace the cracked section of hose or reconnect any loose lines.
   Est. part cost: $10-$50

Rare But Worth Checking

• Cracked Charcoal Canister: → Shop Vapor Canister The plastic housing of the charcoal canister can be damaged by road debris or become brittle with age, causing a large leak. This is usually found during a smoke test.
• Rusted Fuel Filler Neck: → Shop Fuel Filler Neck In areas with heavy road salt use, the metal filler neck where you insert the gas pump nozzle can rust through, creating a large leak that prevents the gas cap from sealing. This was a known issue on some GM vehicles and could be subject to a recall or special coverage program.

Diagnosis Steps

1. Check the Gas Cap: Ensure it is present, tight (clicks multiple times), and the seal is not cracked or worn. If in doubt, replace it with a quality OEM or aftermarket part. Clear the code and drive for a few days to see if it returns.
2. Visual Inspection: Inspect all accessible EVAP hoses in the engine bay and under the vehicle for obvious cracks, damage, or disconnections. Pay close attention to the lines connected to the purge solenoid and charcoal canister.
3. Inspect the Purge Solenoid: Locate the purge solenoid on the engine. With the engine off, disconnect it and try to blow through it. If air passes, it's stuck open and needs replacement.
4. Inspect the Vent Solenoid: Locate the vent solenoid near the charcoal canister at the rear of the car. Check its electrical connection and the attached hoses for damage. It is a normally open valve, so it should allow air to pass when unpowered.
5. Perform a Smoke Test: If the leak is not obvious, the most reliable diagnostic method is a smoke test. A mechanic injects pressurized smoke into the EVAP system (often through the service port) to quickly and accurately find the source of the leak(s).

Parts You'll Likely Need

• Gas Cap (OEM #15846784) — This is the most frequent and simplest fix for a P0455 code. The seal wears out over time.
  Trusted brands: ACDelco (GT294), Stant, Duralast (6836)
  OEM price range: $20-$35
  Aftermarket price range: $15-$25
• EVAP Canister Purge Solenoid Valve (OEM #12597567) — A very common failure item on GM vehicles of this era. It gets stuck open, causing a leak and often a P0496 code as well.
  Trusted brands: ACDelco (214-1680), Dorman, Standard Motor Products (CP470)
  OEM price range: $40-$70
  Aftermarket price range: $25-$50
• EVAP Canister Vent Solenoid Valve (OEM #25932570) — This valve fails due to its location under the car, exposed to the elements. A failure will prevent the system from sealing for its self-test. The original part number 25932570 is often superseded by newer versions.
  Trusted brands: ACDelco (214-2149), Dorman (911-021), Standard Motor Products (CVS6)
  OEM price range: $50-$90
  Aftermarket price range: $30-$60

Related Codes That Often Appear With This One

• P0442 — P0442 indicates a small EVAP leak. You might see this code before or after a P0455 if the leak size is intermittent or if there are multiple leaks of different sizes.
• P0449 — This code specifically points to a fault in the EVAP vent solenoid valve control circuit. If you see P0449 with P0455, the vent solenoid or its wiring is almost certainly the problem.
🎬 See how to test and replace the EVAP vent solenoid.
• P0496 — This code indicates 'EVAP Flow During a Non-Purge Condition,' which is almost always caused by a purge valve that is stuck open. A stuck-open purge valve will also cause a P0455 because it creates a large, permanent leak path to the engine intake.

Platform-Specific Known Issues

• Difficulty Diagnosing Aftermarket Purge Solenoid: → Shop Vapor Canister A user on the ScannerDanner Forum reported issues with a 2007 Aura where even a new aftermarket (Duralast) purge solenoid did not function correctly under vacuum, despite testing fine on the bench. This suggests that some aftermarket parts may not be robust enough to operate under engine vacuum, leading to a misdiagnosis.

Mechanic-Grade Diagnostic Values

• Fuel Tank Pressure (FTP) Sensor Voltage — expected: ~1.5 Volts. Failure: A significantly different voltage reading with the system at atmospheric pressure (e.g., gas cap off or vent solenoid open) can indicate a skewed or faulty FTP sensor, which can falsely trigger a P0455 code.
• EVAP Purge Solenoid Resistance — expected: Approximately 20-40 Ohms (temperature dependent). Failure: An open circuit (infinite resistance) or a short (very low resistance) indicates a failed solenoid coil. While a specific value for the Aura is not documented, a reading of 36 Ohms was noted as good on a similar component.

Scan Tool Commands That Help

• GM Tech 2 / GDS2: EVAP Service Bay Test — This is an automated test to verify a repair without a full drive cycle. The tool commands the ECM to seal the system and run its internal leak test procedure, providing a pass/fail result.
• GM Tech 2 / Professional Bidirectional Scanner: EVAP System Seal / Vent Solenoid CLOSE — This command manually closes the normally-open vent solenoid. This is a critical first step before performing a smoke test to ensure the system is sealed from the atmosphere.
• GM Tech 2 / Professional Bidirectional Scanner: Purge Solenoid Duty Cycle Control — Allows a technician to command the purge solenoid open by a specific percentage (e.g., 0% to 100%) to verify it is not stuck and is responding correctly to the ECM's command, checking for an audible click and change in vacuum.

Wiring & Ground Locations

• EVAP Vent Solenoid — Under the vehicle, near the charcoal canister, mounted to the right side of the fuel tank. Access is difficult and may require lowering the rear of the exhaust system and the fuel tank.. This is a primary component for sealing the EVAP system. Its location makes it prone to damage from road debris and corrosion, and difficult to access for diagnosis and replacement.
• EVAP Purge Solenoid — On top of the engine, near the intake manifold and oil fill cap.. This is the other primary valve in the system. Its location in the engine bay makes it easy to access for testing and replacement.
• G301 / G302 — G301 is located behind the top right rear seat back; G302 is behind the top left.. These are the primary rear body grounds. The EVAP vent solenoid and fuel tank pressure sensor circuits are likely grounded here. A poor connection at these points could cause erratic behavior of rear-mounted EVAP components.
• G107 / G110 — Located on the engine block; G107 on the right front and G110 on the right rear.. These are engine block grounds. The EVAP purge solenoid, being engine-mounted, is likely grounded through one of these points via the engine harness. A corroded or loose ground here could affect purge solenoid operation.

Real Owner Repair Stories

• ScannerDanner Forum (2007 Saturn Aura) — P0455 Gross EVAP Leak code
  ❌ Tried (didn't work) Replacing the EVAP purge solenoid with a new aftermarket (Duralast) part.
  ✅ What actually fixed it The issue was ongoing in the thread, but the critical finding was that the new aftermarket purge solenoid, while testing good on the bench, appeared too weak to open against the 18 inHg of engine vacuum when commanded by a scan tool. This points to a quality issue with the specific aftermarket part, causing a persistent misdiagnosis.
• 2CarPros Forum (2007 Saturn Aura 3.5L) — P0455 code, which later changed to P0449 after replacing the gas cap.
  ❌ Tried (didn't work) Replacing the gas cap (this changed the code but did not fix the underlying issue).
  ✅ What actually fixed it The owner, after being told by a dealer that the part was the EVAP vent solenoid (GM #25932570), located repair manual instructions. The final resolution was not posted, but the owner confirmed the fix required lowering the fuel tank to access the vent solenoid, a job they deemed too difficult to perform themselves on the ground. This story highlights the difficult location of the vent solenoid.
• NHTSA ODI #10566075 — An owner reported a P0455 EVAP leak code occurring alongside several other powertrain issues, including engine misfires (P0300) and variable timing actuator codes (P0016-P0019). The report notes the owner paid for several new sensors and solenoids to address the multiple failures.

"I Checked Everything" — The Actual Cause

• A skewed Fuel Tank Pressure (FTP) sensor can make the ECM believe there is a large leak when the system is perfectly sealed. The sensor might report a pressure drop that isn't real. This would pass a smoke test because there is no physical leak to be found.
• An aftermarket purge valve that is too weak to open against engine vacuum can cause the EVAP monitor to fail, setting a P0455. The valve itself would not leak during a smoke test (as it is normally closed), but its failure to function under operating conditions causes the code.

OEM Part Supersession History

• 25932570 → 13575701 (per GM Parts Giant), 214-2149 (per ACDelco) — Part has been updated or redesigned by the manufacturer.
  Heads up: The part listed as ACDelco 214-2149 is a common service replacement for the original vent solenoid. Ensure the replacement kit comes with any necessary adapter harnesses if the connector style was changed.

Model Year Variations Within This Range

• 2007-2009: The Saturn Aura was available with multiple engines (2.4L I4, 3.5L V6, 3.6L V6). While the EVAP system functions identically, specific part numbers for components like the purge solenoid may differ between engine types. For example, GM Parts Giant lists different part numbers for the 3.5L and 3.6L engines. Always verify the part number with the vehicle's VIN.

Diagnostic Flowchart

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0496 — EVAP Flow During a Non-Purge Condition. This code is explicitly noted to often trigger alongside P0455 on this platform when the EVAP purge solenoid gets stuck open, creating a constant vacuum leak into the intake.
• P0449 — EVAP Vent Solenoid Valve Control Circuit. This code can appear during the diagnostic process for a P0455 (as reported by a 2007 Aura owner) if the vent solenoid at the rear of the vehicle fails electrically or is disconnected.
• P0442 — EVAP System Leak Detected (Small Leak). Shares the exact same root causes as P0455 (loose gas cap, degrading O-rings, cracked hoses). A degrading seal may trigger this small leak code before worsening into a P0455 large leak.
• P0443 — EVAP Purge Control Valve Circuit. Related to the purge solenoid, which is a primary failure point for P0455 on the Aura. Electrical failures or incompatible aftermarket solenoids can trigger circuit codes alongside leak codes.

Frequently Asked Questions