LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Honda >> 2017 >> Pilot Elite >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTC Diagnostics (6 Of 6) >> DTC Troubleshooting >> DTC P2421
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P2421

DTC P2421  : EVAP Canister Vent Shut Valve Stuck Open

Special Tools Required 

- Vacuum Pump/Gauge, 0-30 inHg Snap-on YA4000A or equivalent, commercially available

- Vacuum/Pressure Gauge, 0-4 inHg 07JAZ-001000B

NOTICE: 

The fuel system is designed to allow specified maximum vacuum and pressure conditions.

Do not deviate from the vacuum and pressure tests as indicated in these procedures.

Excessive pressure/vacuum would damage the EVAP components or cause eventual fuel tank failure.

NOTE: 

DTC Description Confirmed DTC Pending DTC
P2421 EVAP Canister Vent Shut Valve Stuck Open    

DTC (PGM-FI)

  1. Problem verification

    - 1. Turn the vehicle to the ON mode.

    - 2. Clear the DTC with the HDS.

    - 3. Turn the vehicle to the OFF (LOCK) mode.

    - 4. Turn the vehicle to the ON mode.

    - 5. Select the EVAP TEST in the INSPECTION MENU, then select the FUNCTION TEST with the HDS.

    FUNCTION TEST

    Is the result OK?

    YES 

    Intermittent failure, the system is OK at this time.

    Check for poor connections or loose terminals at the FTP sensor, the EVAP canister purge valve, the EVAP canister vent shut valve, and the PCM.

    If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot - Refer to: How to Troubleshoot the Fuel and Emissions Systems .

    If the vehicle returns with the same DTC, continue with step 2.

    NO 

    The failure is duplicated. Go to step 2.

  2. EVAP canister vent hose check

    - 1. Check the EVAP canister vent hose (A) for a blockage or a restriction.

    GHH308031Courtesy of HONDA, U.S.A., INC.

    Is there a blockage or a restriction in the hose?

    YES 

    Remove a blockage or a restriction, if needed, replace the EVAP canister vent hose.

    NO 

    Go to step 3.

  3. EVAP canister purge valve leak check

    - 1. Remove the EVAP canister purge valve with its connector and vacuum hose connected.

    - 2. Disconnect the vacuum hose (purge line) (A) from the EVAP canister purge valve (B) in the engine compartment, then connect a T-fitting (C), a vacuum gauge, and a vacuum pump/gauge, 0 - 30 inHg, to the vacuum hose as shown.

    GHH308032Courtesy of HONDA, U.S.A., INC.

    - 3. Slowly apply about 2 kPa (0.6 inHg, 15 mmHg) of vacuum to the hose.

    Does it hold vacuum for 1 minute?

    YES 

    Leak not detected at the EVAP canister purge valve. Go to step 4.

    NO 

    Replace the EVAP canister purge valve .

  4. Determine possible failure area (EVAP canister vent shut valve, others)

    - 1. Turn the vehicle to the OFF (LOCK) mode.

    - 2. Disconnect the fuel vent tube (A) from the EVAP canister (B), and plug the EVAP canister port (C).

    GHH308033Courtesy of HONDA, U.S.A., INC.

    - 3. Remove the T-fitting and vacuum pump/gauge, 0 - 30 inHg, and connect the vacuum pump/gauge, 0 - 30 inHg to the vacuum hose (purge line) (A) as shown.

    GHH308034Courtesy of HONDA, U.S.A., INC.

    - 4. Turn the vehicle to the ON mode.

    - 5. Select the EVAP TEST in the INSPECTION MENU, then select EVAP CVS ON in the SINGLE SOLENOID with the HDS.

    SINGLE SOLENOID

    Apply vacuum to the hose until the FTP reads 1.90 V (-0.59 inHg, -15.1 mmHg).

    NOTE:  Be careful not to exceed the vacuum. If you do, the FTP sensor can be damaged.

    Signal Current conditions
    Values Unit
    FTP SENSOR    

    - 7. Check the parameter (s) below with the HDS for 1 minute.

    Signal Current conditions
    Values Unit
    FTP SENSOR    

    Does the voltage increase more than 0.2 V (0.1 inHg, 2.5 mmHg)?

    YES 

    Go to step 5.

    NO 

    Go to step 7.

  5. EVAP canister vent shut valve operation check

    - 1. Select the EVAP TEST in the INSPECTION MENU, then select EVAP CVS OFF in the SINGLE SOLENOID with the HDS.

    SINGLE SOLENOID

    Disconnect the EVAP canister vent hose (A) from the EVAP canister vent shut valve port (B), and plug it.

    GHH308035Courtesy of HONDA, U.S.A., INC.

    - 3. Apply vacuum to the hose until the FTP reads 1.90 V (-0.59 inHg, -15.1 mmHg).

    NOTE:  Be careful not to exceed the vacuum. If you do, the FTP sensor can be damaged.

    Signal Current conditions
    Values Unit
    FTP SENSOR    

    - 4. Check the parameter (s) below with the HDS for 1 minute.

    Signal Current conditions
    Values Unit
    FTP SENSOR    

    Does the voltage increase more than 0.2 V (0.1 inHg, 2.5 mmHg)?

    YES 

    The EVAP canister vent shut valve is OK. Go to step 6.

    NO 

    Replace the EVAP canister vent shut valve .

  6. EVAP canister purge line visual check

    - 1. Check for a poor connection or damaged EVAP canister purge line between the EVAP canister and the EVAP canister purge valve. Also check for damage to the EVAP canister.

    Are the line and the EVAP canister OK?

    1. YES 

      Replace these parts.

      • FTP sensor O-ring
      • EVAP canister vent shut valve case and O-ring
      • EVAP canister

      NO 

      Replace or repair the EVAP canister purge line or the canister.

  7. Fuel fill pipe and fuel vapor hose visual check

    - 1. Select EVAP CVS OFF in the SINGLE SOLENOID with the HDS.

    SINGLE SOLENOID

    Check for a poor connection or damage to the fuel fill pipe and the fuel vapor hose.

    Are the parts and connections OK?

    YES 

    The fuel fill pipe and the fuel vapor hose are OK. Go to step 8.

    NO 

    Repair or replace the damaged parts.

  8. Shut-off valve check

    - 1. Turn the vehicle to the OFF (LOCK) mode.

    - 2. Remove the mis-fuel inhibit device.

    - 3. Check the flap of the shut-off valve (A).

    GHH308036Courtesy of HONDA, U.S.A., INC.

    Is the flap closed?

    YES 

    Go to step 9.

    NO 

    Replace the main flap unit .

  9. Shut-off valve seal check

    - 1. Check the flap seal of the Shut-off valve (A) and the mating surface on the Shut-off valve.

    GHH308037Courtesy of HONDA, U.S.A., INC.

    Is the flap seal missing or damaged, is the Shut-off valve mating surface damaged?

    YES 

    Replace the main flap unit .

    NO 

    The shut-off valve is OK. Check the fuel tank unit O-ring and the fuel tank.