DTC P0455: EVAP System Large Leak Detected; DTC P0456: EVAP System Very Small Leak Detected

NOTE: 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.

Special Tools Required

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

NOTE:

Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
Fresh fuel has a higher volatility that will create greater pressure/vacuum. The best condition for testing is less than a full tank of fresh fuel. If possible, to assist in leak detection, add 1 gallon of fresh fuel to the tank (as long as it will not fill the tank), just before starting these procedures.

Check the fuel fill cap (the cap must say TIGHTEN TO CLICK). It should turn 1/4 turn after it's tight, then it clicks.
Is the correct fuel fill cap installed and properly tightened?

YES -Go to step 2.

NO -Replace or tighten the cap, then go to step 23.
Check the fuel fill cap seal (A) and the fuel fill pipe mating surface (B). Make sure that the fuel fill cap tether cord (C) is not caught under the cap.

Fig 1: Identifying Fuel Fill Cap Seal, Fuel Fill Pipe Mating Surface And Tether Cord
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the fuel fill cap seal missing or damaged, is the fuel fill pipe damaged, or is the tether cord caught under the cap?

YES -Replace the fuel fill cap or the fuel fill pipe, then go to step 23.

NO -Go to step 3.
Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
Do the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.
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, or the EVAP canister vent shut valve, and the PCM.

NO -Go to step 6.
Turn the ignition switch to LOCK (0).
Check for a poor connection or damage at the fuel tank vapor recirculation tube.
Is the tube OK?

YES -Go to step 8.

NO -
- Reconnect or replace the fuel tank vapor recirculation tube, then go to step 23.
- If needed, replace the fuel tank (see FUEL TANK REPLACEMENT ), then go to step 23.
Disconnect the fuel tank vapor recirculation tube (A) from the EVAP canister (B), and plug the EVAP canister port (C).

Fig 2: Identifying Fuel Tank Vapor Recirculation Tube, EVAP Canister And Port
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Remove the intake air duct (air flow tube) (see step 20 under TURBOCHARGER AND EXHAUST MANIFOLD REMOVAL AND INSTALLATION ).
Disconnect the vacuum hose (purge line) (A) from the EVAP canister purge valve (B) in the engine compartment, then connect a vacuum pump/gauge, 0-30 inHg, to the vacuum hose as shown in illustration.

Fig 3: Identifying Vacuum Hose And EVAP Canister Purge Valve
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch to ON (II).
Select EVAP CVS ON in the INSPECTION MENU with the HDS.
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 pressure. If you do, the FTP sensor can be damaged.
Monitor the FTP SENSOR in the DATA LIST for 1 minute with the HDS, and remove the vacuum pump from the purge valve.
Does the voltage increase more than 0.2 V (0.1 inHg, 0.5 mmHg)?

YES -Go to step 15.

NO -Go to step 20.
Select EVAP CVS OFF in the INSPECTION MENU with the HDS.
Disconnect the fresh air hose (A) from the EVAP canister (B), and plug the EVAP canister ports (C).

Fig 4: Identifying Fresh Air Hose, EVAP Canister And Ports
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Apply vacuum to the EVAP system 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.
Monitor the FTP SENSOR in the DATA LIST for 1 minute with the HDS.
Does the voltage increase more than 0.2 V (0.1 inHg, 2.5 mmHg)?

YES -Go to step 19.

NO -Replace the EVAP canister vent shut valve, then go to step 22.
Check for a loose or damaged EVAP canister purge line between the EVAP canister and the EVAP canister purge valve.
Is the line OK?

YES -Replace these parts, then go to step 22:
- FTP sensor O-ring
- EVAP canister vent shut valve case and O-ring
- EVAP canister
NO -Reconnect or repair the EVAP canister purge hose, then go to step 22.
Select EVAP CVS OFF in the INSPECTION MENU with the HDS.
Check these parts for looseness or damage:
- Fuel fill pipe
- Fuel vapor return pipe
Are the parts OK?

YES -Check the fuel tank unit base gasket (see INSTALLATION ), and check the fuel tank, then go to step 22.

NO -Repair or replace the damaged parts, then go to step 22.
Reconnect all hoses and connectors, and reinstall all parts.
Turn the ignition switch to ON (II).
Reset the PCM with the HDS.
Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
Do the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.
Is the result OK?

YES -Troubleshooting is complete.

NO -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. Also check all EVAP line connections, then go to step 1.