What this code means
P2422 may indicate an EVAP-system pressure or venting issue where the PCM sees the fuel tank pressure signal outside the expected behavior.
What the vehicle may do
- The vehicle may show a warning light.
- The driver may not notice a major drivability symptom.
- The code can often be tied to EVAP venting behavior rather than engine performance.
Possible fault areas
- Possible restricted EVAP vent hose or FTP sensor vent hose.
- Possible EVAP canister vent shut valve concern.
- Possible FTP sensor concern.
- Possible EVAP canister concern.
Diagnostic path
Open on what P2422 is telling you
On this Civic, P2422 is an EVAP-system fault where the PCM may be seeing the fuel tank pressure signal outside the range it expects during venting checks. The driver may not notice much beyond a warning light, but the fault can involve restricted EVAP venting, the canister vent shut valve, the FTP sensor vent path, the FTP sensor itself, or the canister. Start with the basic system checks and follow a structured diagnostic approach. If other EVAP codes are present, check what they mean first, but keep this diagnostic focused on P2422.
Use the FTP sensor reading to choose the path
First, get the emergency fuel funnel from the trunk tool box and insert it into the fuel filler neck. Then look at HDS [FTP Sensor]. If it indicates -0.67 - 0.67 kPa, use the path that includes the EVAP canister vent hose and the EVAP canister vent shut valve before moving into the shared checks. If it does not indicate -0.67 - 0.67 kPa, move into the shared FTP sensor vent hose, FTP sensor, and EVAP canister checks. That first reading helps keep the diagnostic efficient instead of testing every possible item the same way every time.
Confirm the fault status before component testing
Now confirm the operating condition for the fault. Start the engine and let it idle with no load until the radiator fan comes on. For a CVT, use P or N. For a manual transmission, use neutral. Then monitor HDS [EVAP PC Duty] while holding the engine at 3,000 rpm with HDS [EVAP PC Duty] at 20 % or more for at least 4 minutes, then let the engine return to idle. Watch HDS [OBD STATUS (PGM-FI)] for P2422 and any related EVAP status. Keep this confirmation separate from the component inspections that come next.
If the first path applies, inspect the canister vent hose
If the initial FTP sensor reading put you on the path that includes the canister vent side, begin with the EVAP canister vent hose. Disconnect the hose and check it for blockage or restriction. A normal hose has no blockage or restriction. If the hose is abnormal, call that out as the problem area.
Then check the canister vent shut valve operation
Next on that same path, remove the EVAP canister vent shut valve. Connect the 2P connector to the valve, turn the vehicle to ON mode, and command HDS [CVS ON]. Check the valve operation. Normal here means the valve is free of corrosion and operates properly. If it is abnormal, the problem area is the EVAP canister vent shut valve.
Inspect the FTP sensor vent hose on either path
Both diagnostic paths come back to the FTP sensor vent hose. Disconnect the FTP sensor vent hose and check it for blockage or restriction. Normal is no blockage or restriction. If it is abnormal, identify the FTP sensor vent hose as the problem area.
Check the FTP sensor port reading
Next, disconnect the FTP sensor vent hose from the FTP sensor. Remove the FTP sensor from the EVAP canister with its connector still connected. Turn the vehicle to ON mode and confirm HDS [FTP Sensor]. A normal reading is -0.67 - 0.67 kPa. If that reading is abnormal, identify the FTP sensor as the problem area.
Use the canister as the last call in this path
If the earlier inspection items all showed normal results, the remaining fault area in this diagnostic path is the EVAP canister. The takeaway is simple: use the FTP sensor reading to choose the path, confirm the code status under the required operating condition, then work through the vent path, valve operation, FTP venting, FTP sensor reading, and finally the canister without guessing. For more diagnostic training, visit stepdiagnostics.com.
Final check
P2422 can often be approached by confirming the FTP sensor behavior, then separating vent-path checks from sensor and canister checks.
For more guided automotive diagnostics, visit STEP Diagnostics.
