P0455 on 2000-2007 GMC Yukon: EVAP Large Leak Causes and Fixes

What's Unique About the 2000-2007 Gmc YUKON

For the 2000-2007 GMC Yukon, which spans the GMT800 (2000-2006) and the first year of the GMT900 (2007) generations, EVAP system components are common failure points due to age and exposure. The vent solenoid, located above the spare tire, is particularly vulnerable to dirt and moisture, a known design flaw. GM acknowledged this by issuing TSBs like 01-06-04-037 and later creating updated parts that relocate the solenoid's air filter to a cleaner location, like the top of the transmission bell housing, to prevent repeat failures.

Diagnostic Flowchart

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

Generation note: This range covers two generations: the GMT800 (2000-2006) and the start of the GMT900 (2007). While the EVAP system's function is the same, the exact location and part numbers for components like the vent solenoid can differ. For example, the vent solenoid on many GMT800 models is near the charcoal canister above the rear axle, often above the spare tire. Later models and service replacements often use a relocation hose to move the filter to a less exposed area.

Symptoms You May Notice

• Check Engine Light is on
• A noticeable fuel smell, especially around the rear of the vehicle.
• Potentially a whooshing sound when removing the gas cap if the vent system is clogged.
• Difficulty filling the fuel tank (gas pump nozzle clicks off repeatedly), which strongly points to a stuck-closed or clogged vent solenoid.

Most Likely Causes

1. Loose, Damaged, or Incorrect Gas Cap 🔴 High Probability This is the most common cause for any vehicle. The cap's rubber seal can dry out and crack over time, or it may simply not have been tightened correctly after refueling. Many owners solve the P0455 code simply by replacing the gas cap with a new OEM part.
   How to confirm: First, tighten the cap until it clicks several times. Clear the code and drive for a few days. If the code returns, inspect the cap's rubber O-ring for cracks or brittleness. If you hear a loud whoosh of pressure when removing the cap, the problem is more likely a clogged vent system rather than a leaking cap.
   Typical fix: Replace the gas cap with a quality OEM part like ACDelco. Aftermarket caps can sometimes cause sealing issues.
   Est. part cost: $15-$30
2. Faulty EVAP Vent Solenoid (Canister Vent Valve) 🔴 High Probability Located near the rear axle and spare tire, this part is highly exposed to road debris, dust, and moisture, causing it to fail. It can get stuck open (creating a leak) or get clogged with dirt and fail to close, which also causes a leak during the system self-test. This is a very common failure on GMT800/900 trucks.
   How to confirm: The valve is normally open and closes when 12V is applied. A mechanic can command it closed with a scan tool during a smoke test. A DIY test involves removing the valve and applying 12V to its terminals; you should hear a distinct click as it closes. If it's clogged with dirt, it may not function even if it clicks. Difficulty fueling is another strong indicator. 🎬 Watch: How to replace both the vent and purge valves.
   Typical fix: Replace the EVAP vent solenoid. It is often sold as a kit with a new hose and filter to relocate the air intake to a cleaner spot, per GM's updated design.
   Est. part cost: $30-$70
3. Faulty EVAP Purge Solenoid (Purge Valve) 🟡 Medium Probability This valve is located on top of the engine intake manifold and is subjected to heat cycles. It can fail by getting stuck open, creating a constant vacuum leak that the computer interprets as a large EVAP leak.
   How to confirm: The purge valve is normally closed. Disconnect the hoses and the electrical connector, remove the single 8mm bolt, and take the valve off the engine. Try to blow through it. If air passes, it is stuck open and needs to be replaced.
   Typical fix: Replace the purge solenoid. This is typically a 10-minute job requiring only an 8mm socket. 🎬 See this walkthrough for diagnosing a large EVAP leak.
   Est. part cost: $25-$50
4. Cracked or Disconnected EVAP Hoses ⚪ Low Probability Over two decades, the plastic and rubber hoses in the EVAP system can become brittle and crack. A surprisingly common failure point found by owners is a cracked rubber elbow on the PCV vacuum line on the intake manifold, which can be mistaken for an EVAP leak by the system.
   How to confirm: A visual inspection may reveal obvious cracks or disconnections. The most effective method is a smoke test, which forces smoke into the EVAP system, making any leaks visible. Be sure to inspect all vacuum lines on the intake manifold, not just the EVAP lines.
   Typical fix: Replace the damaged hose section. For the PCV elbow, a piece of 5/16" fuel line is a common DIY repair.
   Est. part cost: $10-$40

Rare But Worth Checking

• Cracked Charcoal Canister: The canister itself can be damaged by road debris or develop cracks from age, creating a large leak. This is usually found during a smoke test if other components check out. Sometimes the canister fails internally, sending charcoal pellets into the EVAP lines and clogging valves.
• Leaking Fuel Filler Neck: On older trucks, especially in rust-prone areas, the metal fuel filler neck can corrode and develop holes, which will cause a large EVAP leak. There was a recall for this on some related GM models, so it's a known potential failure point.
• Leaking Fuel Tank Gasket: The gasket for the fuel pump/sending unit on top of the tank can dry out and fail, causing a large leak. This is often found with a smoke test and may be accompanied by a fuel smell after filling up.

Diagnosis Steps

1. Read the Code: Confirm P0455 is the active code with an OBD-II scanner.
2. Check Gas Cap: Ensure the gas cap is tight and clicks at least three times. Inspect the rubber seal for cracks or damage. If in doubt, a new ACDelco cap is an inexpensive and reliable first step.
🎬 Watch: A quick DIY guide to fixing the P0455 code.
3. Visual Inspection: Look over the EVAP hoses in the engine bay (especially vacuum elbows on the intake manifold) and under the truck near the fuel tank for any obvious cracks, damage, or loose connections.
4. Test Purge Valve: Locate the purge valve on the engine intake. Disconnect it and try to blow through it. If air passes, it's stuck open and needs replacement. This is a very common and easy-to-check failure.
5. Test Vent Valve: Locate the vent valve near the spare tire. Check for heavy dirt/debris. Apply 12V power to its terminals to see if it clicks loudly. A lack of a click or heavy contamination indicates it needs replacement.
6. Smoke Test: If the leak source is still not found, a smoke test is the definitive next step. A mechanic (or a DIYer with a smoke machine) will inject low-pressure smoke into the EVAP system's service port. Smoke will exit from the point of the leak, whether it's a cracked hose, a bad seal on the filler neck, or a faulty canister.

Parts You'll Likely Need

• Gas Cap (OEM #ACDelco GT284 or GT330 (verify by year)) — This is the most frequent and cheapest fix. The seal wears out over time. Using an OEM cap is recommended as some aftermarket caps don't seal correctly.
  Trusted brands: ACDelco, Stant
  OEM price range: $20-$35
  Aftermarket price range: $15-$25
• EVAP Vent Solenoid / Canister Vent Valve (OEM #ACDelco 25932571 (original style), ACDelco 23481275 (updated kit)) — This part is highly prone to failure from dirt and moisture exposure. Its failure is a primary cause of P0455 and P0449 codes. The updated kit (often Dorman 911-030) includes a hose to relocate the filter away from debris.
  Trusted brands: ACDelco, Dorman (p/n 911-030)
  OEM price range: $40-$60
  Aftermarket price range: $25-$45
• EVAP Purge Solenoid / Purge Valve (OEM #ACDelco 214-1680 (replaces 12597567)) — This engine-mounted valve can get stuck open due to heat and age, causing a leak. It's a quick and common replacement.
  Trusted brands: ACDelco, Bosch, Dorman (p/n 911-032)
  OEM price range: $35-$50
  Aftermarket price range: $20-$40

Related Codes That Often Appear With This One

• P0442 — P0442 indicates a small EVAP leak. You might see this code alongside P0455 if the system has multiple leaks or if a failing component is creating an intermittent leak that the computer interprets differently on separate tests.
• P0449 — This code specifically points to a malfunction in the EVAP vent solenoid circuit. If you have P0455 and P0449 together, the vent solenoid or its wiring is almost certainly the culprit.

Technical Service Bulletins (TSBs) & Recalls

• 21-NA-124: Diagnostic tips for testing EVAP system leaks causing P0442 and/or P0455.
• 01-06-04-037: Addresses EVAP codes related to the vent solenoid design, recommending an updated part with a filter relocation kit to prevent dust/water intrusion.

Platform-Specific Known Issues

• A Technical Service Bulletin #21-NA-124 was issued in 2022 providing diagnostic tips for finding EVAP leaks related to code P0455 on 2007 models.

Mechanic-Grade Diagnostic Values

• EVAP Canister Purge Valve Solenoid Resistance — expected: 15 to 30 Ohms. Failure: A reading significantly outside this range indicates a damaged internal coil.
• Fuel Tank Pressure (FTP) Sensor Voltage (Key On, Engine Off, gas cap removed) — expected: ~1.5 Volts. Failure: A reading significantly different, such as below 1.0V or above 2.0V, indicates a faulty sensor or a wiring issue. High voltage indicates vacuum, low voltage indicates pressure.
• FTP Sensor Signal Range — expected: 0.1V to 4.9V. Failure: A voltage reading stuck at either extreme or that doesn't change when pressure/vacuum is applied indicates a failed sensor or circuit fault.
• EVAP Vent Solenoid Circuit Voltage (at connector) — expected: Approximately 12V (B+) on the power feed wire.. Failure: Absence of 12V indicates a wiring or fuse issue. The ground-side control wire will also show 12V until the PCM commands the solenoid ON, grounding the circuit.

Scan Tool Commands That Help

• Tech2 / GDS2 or equivalent professional scanner: EVAP Service Bay Test — To run a complete, automated test of the EVAP system. The tool will automatically seal the system and monitor pressure decay to determine if a leak is present.
• Tech2 / GDS2 or equivalent professional scanner: EVAP Vent Solenoid - Command ON/OFF — To manually close the normally-open vent valve to seal the system for a smoke test or to confirm the solenoid is functioning electrically and mechanically.
• Tech2 / GDS2 or equivalent professional scanner: EVAP Purge Solenoid - Command ON/OFF (or Duty Cycle %) — To test the normally-closed purge valve. Commanding it open while blowing into its hose can confirm it opens. It should hold against pressure/vacuum when commanded OFF.

Wiring & Ground Locations

• Fuel Pump / FTP Sensor Ground — On the driver's side frame rail, near the front wheel well. Often two grounds are present; the fuel system ground is typically the upper one.. The Fuel Tank Pressure (FTP) sensor is often part of the fuel pump module and shares this ground. A corroded ground here can cause erratic FTP sensor readings, potentially triggering a false P0455.
• G103 / G104 / G108 — On the rear of the cylinder heads on the engine block.. These are primary grounds for the Powertrain Control Module (PCM). A poor connection here can cause a multitude of seemingly unrelated codes and drivability issues, including incorrect operation of EVAP components controlled by the PCM.
• G401 — On the left rear body mount, near the rear of the vehicle.. This is a major chassis ground for components at the rear of the vehicle. While the vent solenoid is typically grounded through its control circuit, a poor body/frame ground in the area can contribute to electrical issues.
• EVAP System Fuse (2007+ GMT900) — Fuse #4 (15 Amp) in the under-hood fuse block.. This fuse supplies power to the EVAP vent and purge solenoids. If this fuse is blown, the vent valve will be stuck open (its normal state), creating a permanent large leak and setting code P0455.

Real Owner Repair Stories

• YouTube user 'ScottTheFixItGuy' (2004 GMC Yukon) — Check Engine Light with code P0455. A loud 'whoosh' of pressure was heard when removing the gas cap, along with a strong fuel smell.
  ❌ Tried (didn't work) Initially suspected the gas cap, but the whooshing sound indicated the system was sealing, not leaking out.
  ✅ What actually fixed it The EVAP purge valve solenoid on the engine intake was faulty (likely stuck closed, preventing vapors from being purged). Replacing the purge valve, a 10-minute job with an 8mm socket, resolved the code.

"I Checked Everything" — The Actual Cause

• A common scenario is performing a smoke test and finding no visible leaks, yet the P0455 code returns. The cause is often a faulty Fuel Tank Pressure (FTP) sensor. The sensor itself doesn't leak smoke, but it provides incorrect voltage data to the computer, making it believe a large leak exists. The proper diagnosis is to monitor the FTP sensor's voltage on a scan tool while manually applying light pressure or vacuum to the EVAP system. If the voltage reading does not change accordingly, the sensor is bad and must be replaced.

When the Usual Fixes Don't Work

• While a loose gas cap is the most cited cause for P0455, on this specific platform, a loud 'whoosh' of air when removing the cap often points away from a leak and towards a blockage or a stuck-closed valve. In these cases, the purge solenoid on the engine is a more likely culprit than the gas cap, as it's failing to vent the tank's vapor pressure into the engine as designed.

OEM Part Supersession History

• ACDelco 25932571 (also replaces 10382105, 15750484) → ACDelco 23481275 (kit) or Dorman 911-030 (kit) — The original vent solenoid design had its air filter integrated or positioned low, making it highly susceptible to clogging from dust and moisture kicked up by the tires. The updated kits include a long rubber hose to relocate the filter to a clean, dry location like the upper fuel filler neck area.

Model Year Variations Within This Range

• 2000-2006 (GMT800) vs. 2007 (GMT900): While functionally similar, the part numbers for the purge solenoid, vent solenoid, and charcoal canister are different between generations. The mounting hardware for the purge valve can also differ (8mm bolt on GMT800 vs. 10mm nut on some GMT900s).
• 2007 (GMT900): The replacement vent solenoid for 2007 models is almost always the updated kit (e.g., ACDelco 214-2149 or 23481275) which includes a relocation hose to move the filter intake near the fuel filler neck for protection.
• 2007 (GMT900): The under-hood fuse box layout is different from the GMT800 models. The fuse powering the EVAP solenoids is located at position #4 in the 2007+ trucks.