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 in these procedures. Excessive pressure/vacuum will damage the EVAP components or eventually cause fuel tank failure.

Special Tools Required

Vacuum/Pressure Gauge, 0-4 In.Hg, 07JAZ-001000B
Vacuum Pump/Gauge, 0-30 In.Hg, 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 creates 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 24.
Check the fuel fill cap seal (A) and the fuel fill pipe mating surface (B). Make sure 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 Fuel Fill Cap 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 24.

NO -Go to step 3.
Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
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 7.

NO -
- Reconnect or replace the fuel tank vapor recirculation tube, then go to step 26.
- If needed, replace the fuel tank (see FUEL TANK REPLACEMENT ), then go to step 26.
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 in.Hg, to the EVAP canister purge valve as shown.

Fig 2: Disconnecting Vacuum Hose (Purge Line) From EVAP Canister Purge Valve In Engine Compartment
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Slowly apply about 2 kPa (0.6 in.Hg, 15 mmHg) of vacuum to the hose.
Does it hold vacuum for 1 minute?

YES -Go to step 9.

NO -Replace the EVAP canister purge valve, then go to step 25.
Turn the ignition switch to ON (II).
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, the EVAP canister vent shut valve, and the ECM/PCM.

NO -Go to step 11.
Turn the ignition switch to LOCK (0).
Disconnect the fuel tank vapor recirculation tube (A) from the EVAP canister (B), and plug the EVAP canister port (C).

Fig 3: Identifying Fuel Tank Vapor Recirculation Tube, EVAP Canister And EVAP Canister Port
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Remove the vacuum gauge, then connect the vacuum pump/gauge, to the vacuum hose (A) as shown.

Fig 4: Identifying Vacuum Hose
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 in.Hg,-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 in.Hg, 0.5 mmHg)?

YES -Go to step 18.

NO -Go to step 23.
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 vent shut valve port (C).

Fig 5: Identifying Fresh Air Hose, EVAP Canister And EVAP Canister Vent Shut Valve Port
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Apply vacuum to the EVAP system until the FTP reads 1.90 V (-0.59 in.Hg,-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 in.Hg, 2.5 mmHg)?

YES -Go to step 22.

NO -Replace the EVAP canister vent shut valve, then go to step 25.
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 25:
- FTP sensor O-ring
- EVAP canister vent shut valve O-ring
- EVAP canister
NO -Reconnect or repair the EVAP canister purge hose, then go to step 25.
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 FUEL TANK UNIT REMOVAL AND INSTALLATION ), and check the fuel tank, then go to step 25.
  
  NO -Repair or replace the damaged parts, then go to step 25.
Reconnect all hoses and connectors.
Turn the ignition switch to ON (II).
Reset the ECM/PCM with the HDS.
Do the ECM/PCM idle learn procedure (see ECM/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 ECM/PCM, then go to step 1.