K20Z3 engine

Check the fuel fill cap (the cap must say "TIGHTEN TO CLICK"). It should turn 1/4 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 13.
Check the fuel fill cap seal (A) and the fuel fill pipe mating surface (B). Verify that the fuel fill cap tether cord (C) is not caught under the cap.

Fig 1: Identifying Fuel Fill Cap Seal And Fuel Fill Pipe Mating Surface
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 13.

NO | Go to step 3.
Reinstall and tighten the fuel fill cap.
Clear the DTC with the HDS.
Start the engine. Hold the engine speed at 3,000 RPM (min^'1 ) without load (in neutral) until the radiator fan comes on, then let it idle for 1 minute.
Test drive at 72 km/h (45 mph) 1 minute or more.
Does fuel cap warning message come on?

YES | Go to step 7.

NO | Intermittent failure, the system is OK at this time.
Turn the ignition switch OFF.
Disconnect the vacuum hose (A) from the EVAP canister purge valve (B) in the engine compartment, and connect a T-fitting (C) between the vacuum gauge and the vacuum pump/gauge 01 30 in.Hg, and the EVAP canister purge valve as shown.

Fig 2: Connecting T-Fitting Between Vacuum Gauge And Vacuum Pump And EVAP Canister Purge Valve
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch ON (II).
Apply about 2 kPa (15 mmHg, 0.6 in.Hg) of vacuum to the hose.
Select the EVAP PCS ON in the INSPECTION MENU with the HDS.
Does the vacuum release momentary?

YES | Check for blockage at the EVAP canister purge line between EVAP canister purge valve and the EVAP canister, then go to step 12.

NO | Replace the EVAP canister purge valve (see EVAP CANISTER VENT SHUT VALVE REPLACEMENT ), then go to step 12.
Reconnect all hoses.
Turn the ignition switch ON (II).
Reset the ECM with the HDS.
Do the ECM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
Start the engine. Hold the engine speed at 3,000 RPM (min^'1 ) without load (in neutral) until the radiator fan comes on, then let it idle for 1 minute.
Test drive at 72 km/h (45 mph) for 1 minute or more.
Does the fuel cap message come on?

YES | Go to step 1 and recheck.

NO | Troubleshooting is complete.