P0446 on 2014-2019 Chevrolet Corvette: EVAP Vent Circuit Causes and Fixes

What's Unique About the 2014-2019 Chevrolet Corvette

On the C7 Corvette, this code is uniquely tied to a very common owner complaint: extreme difficulty when refueling. 🎬 Watch: Why the gas pump keeps shutting off during refueling While many cars might be tricky to fill, a P0446 on a C7 almost guarantees the gas pump will click off every few seconds. This is because the faulty component, the EVAP vent valve, gets stuck closed and prevents air from escaping the tank as fuel goes in. Thankfully, GM placed the entire canister and vent valve assembly in a very accessible location in the rear passenger-side wheel well, making diagnosis and repair much easier than on vehicles where the fuel tank must be dropped.

Symptoms You May Notice

• Check Engine Light is on.
• Extreme difficulty refueling (gas pump nozzle shuts off repeatedly).
• A 'hiss' sound may be heard when opening the gas cap if pressure is trapped, though this is less common with the capless system.
• Inability to fill the tank completely; owners report only being able to add ~13 gallons before the pump constantly shuts off, whereas a functioning system allows a full 17+ gallon fill-up.

Most Likely Causes

1. Faulty EVAP Vent Valve Solenoid 🔴 High Probability → Shop Vapor Canister The solenoid is a moving part that is commanded open and closed frequently. Over time, it can fail mechanically (get stuck closed) or electrically. Its location in the wheel well exposes it to road grime and moisture.
   How to confirm: Use a bidirectional scan tool to command the vent valve open and closed. Alternatively, remove the valve and apply 12V power to its terminals; 🎬 See how to test and replace the vent shut valve you should hear a distinct click as it actuates. The valve is normally open, so you should be able to blow through it when de-energized. If it's stuck closed, it will cause the refueling issue.
   Typical fix: Replace the vent valve solenoid. It is located on the charcoal canister assembly and can be purchased separately.
   Est. part cost: $20 - $80
2. Clogged Charcoal Canister 🟡 Medium Probability → Shop Vapor Canister This is almost always caused by habitually 'topping off' the fuel tank. Forcing extra fuel in after the pump initially stops can push liquid gasoline into the canister, which is only designed to handle vapor. The liquid fuel saturates and ruins the activated charcoal, creating a blockage.
   How to confirm: After removing the canister assembly, check for signs of raw fuel, fuel stains, or a heavy fuel smell from the canister itself. The canister may also feel unusually heavy if saturated. Some owners have confirmed the canister was the issue by disconnecting it and successfully refueling without the pump clicking off.
   Typical fix: Replace the entire charcoal canister assembly. 🎬 Watch this walkthrough on how to replace the charcoal canister The vent valve is often replaced at the same time as a preventative measure.
   Est. part cost: $180 - $250
3. Blocked or Kinked Vent Hoses ⚪ Low Probability The vent hoses run near the wheel well and can be susceptible to debris, spider webs, or insect nests clogging the fresh air inlet.
   How to confirm: Visually inspect all hoses connected to the charcoal canister and vent valve. Disconnect them and attempt to blow compressed air through them to check for blockages.
   Typical fix: Clear the blockage or replace the damaged hose section.
   Est. part cost: $10 - $30
4. Damaged Vent Solenoid Wiring or Connector ⚪ Low Probability The location in the wheel well exposes the wiring to moisture and road debris, which can lead to corrosion or physical damage over time. The harness can also be damaged during a cat-back exhaust installation.
   How to confirm: Inspect the electrical connector and wiring going to the vent solenoid for any green corrosion, frayed wires, or breaks. Use a multimeter to check for 12V at the connector with the key on.
   Typical fix: Repair the damaged wire or clean/replace the connector.
   Est. part cost: $5 - $25

Rare But Worth Checking

• Dust Intrusion into EVAP System: General Motors issued TSB 23-NA-073 for some vehicles operated in extremely dusty environments, where dust can clog the EVAP canister and vent solenoid. While not specific to Corvette, it's a known GM issue. Another TSB, PI1124A, also addresses hard-to-fill conditions caused by dirt/dust intrusion and advises checking for this before replacing parts.
• Fuel Tank Structural Issues: → Shop Fuel Tank Although reported on different GM models, NHTSA ODI #11363765 notes that structural stressing can cause leaks at the tank and fuel pump module connector, which may trigger P0446 along with other codes like P0451.

Diagnosis Steps

1. Confirm the code P0446 with an OBD-II scanner.
2. Note the symptoms. If you are experiencing extreme difficulty when refueling, the problem is almost certainly a blockage in the vent path (valve or canister).
3. Safely raise the vehicle and remove the rear passenger-side wheel.
4. Remove the plastic wheel well liner to expose the charcoal canister and vent valve assembly.
5. Visually inspect the vent valve's electrical connector and wiring for any signs of damage or corrosion.
6. Inspect all attached hoses for kinks, cracks, or obvious blockages from debris or insect nests.
7. If you have a bidirectional scanner, command the vent valve to open and close. Listen for a clicking sound. The inability to refuel suggests the valve is stuck closed.
8. If no scanner is available, remove the vent valve. Apply 12V directly to its terminals and listen for a click. Test if you can blow through it when de-energized (it should be open) and if it seals when energized (closed).
9. If the valve works but the problem persists, the charcoal canister is likely clogged. Remove the canister and check for signs of fuel saturation or excessive weight. One owner on YouTube confirmed the canister was the issue by disconnecting it, which then allowed him to refuel normally.
10. If all components seem to work, check the vent hoses for hidden blockages from debris or insect nests by blowing compressed air through them.

Parts You'll Likely Need

• EVAP Vapor Canister Vent Valve Solenoid (OEM #13576005) — This is the most common failure point. It's a solenoid that gets stuck, preventing the fuel tank from venting during refueling.
  Trusted brands: ACDelco, Dorman
  OEM price range: $40-$80
  Aftermarket price range: $20-$50
• EVAP Charcoal Canister (OEM #84546365 (supersedes 22785596)) — This part gets clogged with fuel if the gas tank is repeatedly overfilled, causing a blockage that triggers P0446 and refueling issues.
  Trusted brands: ACDelco
  OEM price range: $180-$250
  Aftermarket price range: $120-$180

Technical Service Bulletins (TSBs) & Recalls

• 23-NA-073: Evaporative DTCs P0442, P0446, P0455 or P0449, Caused by Dust Intrusion into the Evaporative Canister and Canister Vent Solenoid.
• PI1124A: Addresses hard-to-fill conditions and EVAP codes like P0446 caused by dirt, dust, or water getting into the EVAP canister vent system.

Platform-Specific Known Issues

• Owner Experience: Solenoid and Canister Replacement: A CorvetteForum user with a 2019 Z06 experienced P0446 along with the classic symptom of the gas pump clicking off over 20 times during a fill-up. After confirming the vent and purge solenoids were functioning with a scan tool, they suspected the charcoal canister. They replaced both the canister (approx. $180) and the vent solenoid (approx. $23) and reported the problem was completely fixed, allowing for a smooth, click-free refueling.

Mechanic-Grade Diagnostic Values

• EVAP Canister Vent Valve Solenoid Coil Resistance — expected: 10 - 30 Ohms. Failure: A reading of infinite resistance (OL) means the coil is open. A reading near 0 Ohms indicates a shorted coil. Some sources cite a tighter range of 20-30 Ohms.
• Voltage at Vent Solenoid Connector (Power Wire) — expected: ~12 Volts (Battery Voltage) with Key On, Engine Off. Failure: 0 Volts indicates a blown fuse or a break in the power wire from the underhood fuse block.
• Fuel Tank Pressure (FTP) Sensor Voltage — expected: Approximately 1.5 Volts at atmospheric pressure (Key On, Engine Off).. Failure: A reading stuck high (near 5V) or low (near 0V) can indicate a faulty sensor, which may indirectly contribute to or be caused by the P0446 fault condition. A high voltage (e.g., 4.8V) can indicate a deep vacuum in the tank, consistent with a vent blockage.

Scan Tool Commands That Help

• GDS2 / High-End Bidirectional Scanner: EVAP Vent Solenoid Valve Control — This is a primary diagnostic step. Use this command to manually open and close the vent solenoid. Listen for an audible click from the solenoid in the rear passenger wheel well. If it clicks, the electrical circuit and solenoid coil are likely good, and the problem is a mechanical blockage in the valve itself or the canister. If it does not click, it points to a wiring, fuse, or solenoid electrical failure.

Wiring & Ground Locations

• Underhood Fuse Block Fuse #13 — In the main fuse block in the engine compartment.. This 15A or 25A fuse (labeled ECM/MRRTD) provides the 12V power to the EVAP vent solenoid. If this fuse is blown, the solenoid will have no power, causing a P0446 or P0449 circuit code.
• G401 / G402 — On the frame rail, forward of the rear axle. G401 is on the left (driver's) side, G402 is on the right (passenger's) side.. G402 is the primary ground point for the rear components of the vehicle, including the fuel pump and EVAP system. A corroded or loose ground at this location can cause intermittent or total failure of the vent solenoid circuit, leading to a P0446 code.
• Vent Solenoid Connector — Attached to the EVAP vent solenoid (13576005) in the rear passenger wheel well.. This 2-pin connector provides power and ground control to the solenoid. The Red/White wire is typically the 12V power feed from fuse #13, and the White wire is the control wire that the ECM grounds to activate the solenoid. Testing for voltage here is a key diagnostic step.

Real Owner Repair Stories

• CorvetteForum user (2006 Chevrolet Corvette) — P0446 code, gas spitting back during fill-ups, Check Engine Light.
  ❌ Tried (didn't work) The vent solenoid was tested and found to be functional., All EVAP lines were checked with 30 PSI of air and found to be clear.
  ✅ What actually fixed it The user tried blowing 30 PSI of air into the EVAP canister itself and found it was blocked. After increasing the pressure to 50 PSI, a puff of gas-smelling air was released, clearing the blockage. This resolved the fill-up issue and the P0446 code without replacing any parts.
• CorvetteForum user 'ericp1969' (2019 Corvette Z06) — P0446 code, gas pump nozzle clicking off 20+ times during fill-up.
  ❌ Tried (didn't work) Initial diagnosis with a scan tool showed the vent and purge solenoids appeared to be functioning correctly under commanded tests.
  ✅ What actually fixed it Suspecting a partially clogged charcoal canister based on the symptoms and the fact the code was only thrown under hard acceleration, the owner replaced both the charcoal canister and the vent valve solenoid. This completely solved the refueling problem and cleared the P0446 code.
• GM Owner Report — An owner reported a P0446 code for "EVAP vent performance" after failing an emissions test (NHTSA ODI #10457176). Another owner noted that a dealership found a bulletin for P0446 describing a restricted or blocked EVAP vent path, which required replacing the EVAP vent valve solenoid (NHTSA ODI #10494422).

OEM Part Supersession History

• 22785596 → 84546365 — Standard part lifecycle update by GM. Functionality remains the same.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Cracked/Bent Wheels (Z06 & Grand Sport) 🔴 High — A widely reported issue for Z06 (2015-2019) and Grand Sport (2017-2019) models, leading to multiple class-action lawsuits. Wheels are cast aluminum and allegedly prone to cracking or bending under normal driving conditions, causing air leaks or potential blowouts.
• 8-Speed (A8) Automatic Transmission Shudder 🟠 Medium — Common on 2015-2019 models with the 8L90 automatic transmission. Owners report a vibration or shudder during light acceleration. The issue was traced to the original transmission fluid. (Ref: TSB 18-NA-355: This bulletin prescribes a 'triple flush' procedure to replace the original fluid with an updated Mobil 1 Synthetic LV ATF HP fluid, which usually resolves the issue if caught early.)
• Infotainment Screen Failure / Black Screen 🟡 Low — Reported across C7 model years, symptoms include a flickering or completely black screen. The issue can be intermittent. Causes range from a faulty HMI module to loose wiring connectors behind the screen, sometimes exacerbated by the movement of the motorized screen.
• Serpentine Belt Tensioner Failure 🟡 Low — Identified by a major Corvette specialty shop as the most common non-maintenance part failure they see. The tensioner's internal damper leaks fluid, causing it to become coated in oily grime. The pulley bearing can also fail, causing a squeaking noise.
• Various Electrical Issues (Poor Ground) 🟠 Medium — A poor ground connection (specifically G218 under the driver's side dash) or high resistance in battery cables can cause a wide array of seemingly unrelated electrical problems. (Ref: TSB 18-NA-161: Addresses symptoms like 'Service Stabilitrak' messages, stalling, blank instrument panels/radio, and numerous communication DTCs by outlining procedures to test and fix poor battery/ground connections.)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used EVAP vent valve solenoid (13576005) can be a reasonable choice if sourced from a low-mileage, non-accident donor car. The wiring harness and connectors are also good candidates for used parts if the original is damaged.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For solenoids, test the part by applying 12V and listening for a solid click before installation.
• Inspect plastic housings for any cracks or brittleness.
• Check electrical connectors for any signs of corrosion (green crust) or bent pins.

OEM-only on this vehicle (don't cheap out):

• EVAP Charcoal Canister: This is strongly recommended to be purchased new (OEM ACDelco). A used canister carries a very high risk of being saturated with fuel from the donor car being overfilled or from sitting in a junkyard, which is the primary failure mode of the original part. The cost savings do not outweigh the risk of getting a part that is already bad.

Aftermarket brands forum-validated for this vehicle:

• ACDelco (OEM)
• Dorman (For vent solenoid)

Brands owners have reported issues with on this vehicle:

• Unknown or unbranded charcoal canisters from online marketplaces are a significant gamble and should be avoided.

Real Owner Stories

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

Related OBD-II Codes

• P0442 — Cited in TSB 23-NA-073 as a related EVAP DTC caused by dust intrusion into the canister and vent solenoid.
• P0449 — A related EVAP vent circuit code mentioned in TSB 23-NA-073 that often shares the same root cause as P0446.
• P0455 — A large leak EVAP code that can be triggered by the same dust intrusion issues affecting the vent system described in TSB 23-NA-073.

Frequently Asked Questions