EN

Severity: Low Code type: Generic (all makes)

P2422 Code: EVAP System Vent Valve Stuck Closed

The EVAP vent path is blocked, so the tank can't breathe – slow refueling and a whoosh when the cap comes off.

Safety first · Consult a professional

  • Fuel vapor is flammable. No smoking or open flames; work outdoors and fix fuel leaks before driving.

At a glance

Severity: 2/5 – Low2/5

Severity: Low

Meaning
EVAP System Vent Valve Stuck Closed
System
Emission Controls · Powertrain
Safe to drive?
Yes, short term
Typical repair cost
$30–$1,200
DIY difficulty
Moderate

The vent valve lets the charcoal canister draw in fresh air while the engine purges fuel vapor, and lets air escape while you refuel. P2422 means the ECM has seen evidence that this path stays shut when it should be open: typically the tank pressure sensor shows vacuum building up during purge, or the leak test pump can't move air through the vent side. It's one of the most common EVAP complaints on Toyota and Lexus vehicles with a canister pump module, where the vent valve lives inside that module. The valve itself can stick, but just as often the fresh-air line or filter is clogged, or charcoal dust from a canister damaged by repeated overfilling has jammed it.

Can I keep driving? You can drive, but stop topping off the tank after the first click – forcing fuel in pushes liquid into the canister and makes things worse. If fuel spits back out of the filler neck, stop fueling right away.

How to read P2422

How to read P2422P12243224
  1. P Powertrain
  2. 2 Generic (SAE)
  3. 4 Auxiliary emission controls
  4. 22 Specific fault

Symptoms

  • Pump nozzle clicks off every few seconds, filling takes much longer
  • Loud whoosh or sucking sound when the fuel cap is opened after driving
  • Fuel spitting back out of the filler neck at the end of fueling
  • Check engine light, sometimes with P0455 or P0441 also stored
  • Rarely, a popping or crinkling noise from the tank area while driving

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Vent valve stuck inside the canister pump module 32%
  2. Fresh-air inlet, filter or vent hose clogged with dust, mud or insect nests 24%
  3. Charcoal granules from a canister damaged by overfilling blocking the valve 20%
  4. Vent hose kinked, crushed or plugged after tank or underbody work 10%
  5. Tank pressure sensor giving a false vacuum reading 8%
  6. Vent valve control circuit fault leaving the valve energized 6%

Diagnosis step by step

Diagnostic flow: P24221Do the fuel cap test2Watch tank pressure during purge3Check the fresh-air side4Look for charcoal in the lines5Command the vent valve6Verify after repair

  1. Do the fuel cap test

    After a 20- to 30-minute drive, open the fuel cap slowly. A strong sucking sound means the tank is under vacuum and can't vent; a small puff is normal. Note whether refueling has become slow as well.

  2. Watch tank pressure during purge

    With a scan tool, graph the EVAP or tank pressure sensor at idle, then at about 2,500 rpm once the engine is warm. Pressure sinking steadily into vacuum while the purge valve works confirms the vent path is closed.

    Tools: OBD-II scanner

  3. Check the fresh-air side

    Follow the vent hose from the canister or pump module to its open end, often up near the filler neck or on the frame. Pull it off and blow through it; any restriction, mud or insect debris means cleaning or replacing the hose and filter.

    Tools: Flashlight, Pliers

  4. Look for charcoal in the lines

    Remove the hose between the canister and the vent valve or module. Black granules inside mean the canister is breaking down and must be replaced along with the valve, otherwise the new valve will jam too.

    Tools: Flashlight, Screwdriver

  5. Command the vent valve

    Use an active test to open and close the vent valve while listening at the canister. A valve that clicks but still won't pass air is mechanically stuck; no click at all sends you to the wiring and codes like P2419 or P2420.

    Tools: OBD-II scanner

  6. Verify after repair

    Clear the code, drive, and repeat the fuel cap test. The tank should vent freely, refueling should shut off only when full, and the EVAP monitor should complete after an overnight cold soak.

    Tools: OBD-II scanner

Where the parts are

EVAP system: gas cap, canister, purge and vent valves – P2422123456
EVAP system: gas cap, canister, purge and vent valves
  1. 1Gas cap
  2. 2Charcoal canister
  3. 3Purge valve
  4. 4Vent valve
  5. 5Fuel pump
  6. 6Intake manifold

Repair options & costs

RepairDIY?Estimated cost
Clear or replace blocked vent hose and fresh-air filter Yes $30–$150
Replace vent valve or canister pump module No $250–$650
Replace charcoal canister and vent valve together No $450–$1,200
Replace tank pressure sensor No $120–$350

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Notes by brand

Toyota

P2422 is a well-known complaint on Toyota and Lexus vehicles with the canister pump module, including popular models such as Camry, Corolla, RAV4, Highlander, Sienna and the pickups. Owners usually notice the slow-filling pump nozzle before they notice the check engine light; if charcoal is found in the lines, the canister is typically replaced along with the module.

Field data

Honda 5 Accord, Civic, Civic Cng

Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.

Emissions / smog test impact

Will fail

P2422 lights the check engine light and fails an OBD-based smog check. After the repair, a few days of normal driving with overnight parking lets the EVAP monitor finish before the retest.

Frequently asked questions

Why does my gas pump keep clicking off?

As fuel flows in, the air in the tank has to escape through the canister and vent valve. With the vent blocked, pressure builds in the filler neck and trips the nozzle's automatic shutoff over and over.

Did topping off my tank cause this?

It's a common contributor. Squeezing in extra fuel after the first click can send liquid gasoline into the charcoal canister; the charcoal breaks down, and the dust and granules can jam the vent valve.

Is the whoosh when I open the gas cap dangerous?

Not in itself, but it means the tank is being pulled into vacuum. In rare cases the tank can deform, and the purge system can't work properly, so it's worth fixing rather than ignoring.

Can I just clean the vent valve?

Sometimes a valve jammed by dust frees up after cleaning the fresh-air side, but if charcoal is present the canister is failing. On many Toyota models the valve is part of the pump module and isn't sold separately.

Sources