What this code means
P2422 may mean the EVAP system is not venting the fuel tank vapor system the way the ECM/PCM expects, often pointing to pressure behavior that looks restricted or stuck closed.
What the vehicle may do
- The vehicle may drive normally.
- The check engine light can be on.
- EVAP-related readiness may not complete until the fault is addressed.
Possible fault areas
- Possible EVAP canister vent shut valve concern.
- Possible EVAP vent hose or drain joint restriction.
- Possible FTP sensor vent hose or port issue.
- Possible FTP sensor signal concern.
- Possible internal EVAP canister restriction.
Diagnostic path
Opening and setup
On this 2010-2015 Honda Civic with the 1.8 gas engine, P2422 is an EVAP canister vent shut valve stuck closed malfunction. In plain language, the ECM/PCM may be seeing fuel tank pressure behavior that does not make sense when the EVAP system should be venting. The vehicle may drive normally, but the check engine light can be on, and the fault area may be around the EVAP vent shut valve, the vent hoses and drain joint, the FTP sensor area, or an internal canister restriction. Before getting into the checks, record the stored data and any captured snapshot information, and start with the basic system checks so you are not chasing an old or incomplete picture.
Initial FTP sensor check
Start with the EVAP system check. Turn the ignition switch to ON (II), clear the DTC with the HDS, then turn the ignition switch to LOCK (0). Remove the fuel fill cap and wait 1 minute. Turn the ignition switch back to ON (II), then look at FTP SENSOR in the HDS data list. You are looking for the FTP sensor to be between －0.67 and 0.67 kPa (－0.2 and 0.2 inHg, －5 and 5 mmHg), or 2.4 and 2.6 V. If it is in that range, continue to the problem verification. If it is not in that range, skip ahead to checking the FTP sensor vent hose restriction path.
Duplicate the fault under the monitor conditions
Now verify the problem. Install the fuel fill cap, clear the DTC with the HDS, start the engine, and let it idle with no load until the radiator fan comes on. This is the monitor gate for the EVAP test: watch EVAP PC DUTY in the data list while holding engine speed at 3,000 rpm, with EVAP PC DUTY at 20 % or more for at least 4 minutes, then let the engine idle. Now monitor the OBD STATUS for the EVAP fault group that includes P2422. If the HDS shows FAILED, the fault is duplicated, and you move to the EVAP canister vent line check. If it shows PASSED, treat it as a possible intermittent and repeat the captured conditions as closely as you can, including fuel level, engine speed, vehicle speed, and outside temperature. If nothing shows up, check for poor connections or loose terminals between the FTP sensor and the ECM/PCM, and look for blockage at the FTP sensor vent port and vent hose, plus the EVAP canister vent hose and drain joint. If the status is NOT COMPLETED, let the engine idle until the HDS gives a result.
Vent line and vent shut valve checks
If the failure is duplicated, clear the DTC with the HDS, turn the ignition switch to LOCK (0), and disconnect the EVAP canister vent hose from the EVAP canister. Turn the ignition switch to ON (II), then check FTP SENSOR again in the HDS data list. The same normal window applies: between －0.67 and 0.67 kPa (－0.2 and 0.2 inHg, －5 and 5 mmHg), or 2.4 and 2.6 V. If the reading is now in range, check for a blockage in the EVAP canister vent hose or drain tube joint, then move to repair verification. If it is still out of range, check the EVAP canister vent shut valve. Turn the ignition switch to LOCK (0), remove the EVAP canister vent shut valve from the EVAP canister, connect the 2P connector to the valve, turn the ignition switch to ON (II), and command EVAP CVS ON with the HDS. The valve needs to be free of corrosion and operate properly. If it does, the valve is OK and you continue to the FTP sensor vent hose restriction check. If it does not, replace the EVAP canister vent shut valve, then verify the repair.
FTP sensor vent hose, port, canister, and sensor checks
Next is the FTP sensor vent hose restriction check. Disconnect the vent hose from the FTP sensor and watch FTP SENSOR in the HDS data list. Again, the expected range is between －0.67 and 0.67 kPa (－0.2 and 0.2 inHg, －5 and 5 mmHg), or 2.4 and 2.6 V. If the reading comes back into range with the hose disconnected, check for a blockage in the FTP sensor vent hose, then verify the repair. If it does not come into range, the FTP sensor vent hose is OK, so continue to the FTP sensor port restriction check. Turn the ignition switch to LOCK (0), remove the FTP sensor from the EVAP canister with the connector still connected, turn the ignition switch to ON (II), and check FTP SENSOR again. If the reading is now in that same normal range, the FTP sensor port is OK and the EVAP canister has an internal blockage; replace the EVAP canister, then verify the repair. If the reading is still not in range, replace the FTP sensor, then verify the repair.
Verify the repair
Keep verification separate from the testing path. Turn the ignition switch to LOCK (0), install the parts in the reverse order of removal, turn the ignition switch to ON (II), reset the ECM/PCM with the HDS, and do the ECM/PCM idle learn procedure. Then monitor OBD STATUS for the EVAP fault group that includes P2422. If the HDS shows PASSED, troubleshooting is complete. If any other pending or confirmed codes are present, check what they mean next. If the HDS shows FAILED, go back to the beginning and recheck the path instead of guessing. If the HDS shows NOT COMPLETED, hold engine speed at 3,000 rpm with EVAP PC DUTY at 20% or more until a result comes on. The takeaway is to use the FTP sensor reading as your guide: prove whether the restriction is in the vent path, the shut valve, the FTP sensor venting, the canister, or the sensor before calling the repair. For more diagnostic training, visit stepdiagnostics.com.
Final check
This diagnosis uses FTP sensor behavior to narrow down where EVAP venting may be restricted before confirming the repair.
For more guided automotive diagnostics, visit STEP Diagnostics.
