2003 HONDA CIVIC fuel cap

DTC Pl456: EVAP Control(Fuel Tank Svstem)
System Leakage
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 in. Hg A973X-041-XXXXX
This is a two-trip code. Once cleared, it cannot be
reproduced in one trip. Also, cenain specific driving
and ambient conditions must occur before the ECM will
complete the system checks. Additional test drives may
still not meet the specific conditions needed to
reproduce the code.
Follow these troubleshooting procedures carefully to
ensure the integrity of the system and to confirm the
cause of the problem or code.
NOTE: Fresh fuel has a higher volatility that createsgreater pressure/vacuum. The optimum condltlon for
testing is fresh fuel, and must be less than a full tank. lf
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.
Fuel Fill Cap Check
1. Check the fuel fill cap (the cap must say "lf not
tightened 3 clicks check engine light may come
on" ).
ls the proper luel till cap installed and properly
tightened?
YES Go to step 2.
NO- Replace or tighten the cap.I
2. Check the fuel fill cap seal.
ls the tuel fill cap seal missing or damaged?
YES- Replace the fuel fill cap.I
NO The fuelfill cap is OK. Go to step 3.
EVAP Canister Purge Valve Test
3. Disconnect the vacuum hose from the EVAP
canister purge valve (A), and connect a vacuum
oumo to the hose.
A973X-041-XXXXX
Turn the ignition switch ON (ll).
Apply vacuum to the hose.
Does the valve hold vacuum?
YES-The EVAP canister purge valve is OK. Go to
step 11.
NO-Go to step 6.
Turn the ignition switch OFF.
Disconnect the EVAP canister purge valve 2P
connecror.
5.
7.
{cont'd)
11-175

28.
29.
ls thete continuity?
YES-Go to step 28.
NO-Replace the EVAP canister vent shut valve (A)
and o-ring (B).1
Disconnect ECM connector E (31P).
Check for continuity between EVAP canister vent
solenoid valve 2P connector terminal No. 2 and
body ground.
EVAP CANISTER VENT SHUTVALVE 2P CONNECTOR
Wire side o{ female terminals
ls there continuity?
YES-Repair short in the wire between the EVAP
canister vent shut valve and the ECM (E21).1
NO Update the ECM if it does not have the latest
soflware, or substitute a known-good ECM, then
recheck (see page 11-6). lf the symptom/indication
goes away with a known-good ECM, replace the
original ECM.I
30.
Vacuum Hoses and Connections Test
Do the fuel tank vapor control valve test (see page
1 1-187).
ls the fuel tank vapot control valve OK?
YES-Go to step 31.
NO Replace the fueltank vapor control valve.l
Tighten the fuel cap 3 "clicks", then monitorthe
FTP sensor readings with the Honda PGM Tester.
Start the engine. and let it idle for 5 minutes.
Check the FTP sensor readings.
ls the reading above 0.5 kpa (4 mm Hg, 0.16 in.
Hg) pressure, or about 3 V?
YES Update the ECM if it does not have the latest
software, or substitute a known-good ECM, then
recheck {see page 1 1-6). lf the symptom/indication
goes away with a known-good ECfvl, replace the
original ECM.t
NO Check the following parts for leaks:l
. Fueltank (A)
. Fuel fill cap (B)
. Fuel fill pipe (C)
. Fueltank vapor control valve(D). Fueltank vapor recirculation valve (E)
. Fueltank vapor recirculation tube (F)
. Fueltank vapor signaltube (G)
. Fueltank vapor control venttube(H). FTP sensor (J)
- Repair or replace any leaking parts.
5t.
11-179

EVAP System
EVAP Two Way Valve Test
Special Tools Required. Vacuum pump/Gauge,0-30 in. Hg
A973X-041-XXXXX. Vacuum/Pressure cauge.0-4 in. Hg 07JAZ-0010008
1. Remove the fuelfill cap.
2. Disconnect the vapor line from the EVAP two wayvalve (A). Connect it to a T-fitting (B) from thevacuum gauge and the vacuum pump as shown,
07JAZ-0010008
Apply vacuum slowly and continuously while
watching the gauge. The vacuum should stabilize
momentarily at 0.8 2.1 kPa (6 16 mmHg,
0,2 0.6 in.Hg).
lf the vacuum stabilizes {valve opens) below 0.8 kpa(6 mmHg,0.2 in.Hg) or above 2.1 kPa (16 mmHg,
0.6 in.Hg), install a new valve and retest.
11-186
4. Move the vacuum pump hose from the vacuumfitting to the pressure fitting, and move the vacuumgauge hose from the vacuum side to the pressure
side (A) as shown.
Slowly pressurize the vapor line while watching thegauge. The pressure should stabilize momentarilV
above 1.0 kPa (8 mmHg, 0.3 in.Hg).
. lfthe pressure momentarily stabilizes (valve
opens) above 1.0 kPa (8 mmHg,0.3 in.Hg), thevalve is OK.. lf the pressure stabilizes below 1.0 kPa (8 mmHg,
0.3 in.Hg), install a new valve and retest.

FuelTank Vapor Control Valve Test
Special Tools Required
Vacuum Pump/Gauge, 0-30 in. Hg A973X-041-XXXXX
Float Test
1. Make sure the fuel tank is less than half full.
2. Remove the fuel fill cap to relieve fuel tank
pressure, then reinstall the cap.
3. Disconnect the fuel tank vapor recirculation tube
{A), and connect a vacuum PumP to it.
Plug the line (B).
Apply vacuum to the fuel tank vapor recirculation
tuDe.
lf the vacuum holds, replace the fuel tank vapor
control valve (see page 11-189).
lf the vacuum does not hold, the float is OK. Do
the valve test.
5.
A973X-041-XXXXX
Valve Test
1. N4ake sure the fuel tank is less than half full
2. Remove the fuel fill cap.
3. Disconnect the fuel tank vapor signal tube (A).
Disconnect the vacuum hoses (A) from the EVAP
canister (B), then plug the ports with plugs (C)4.
A973X-O41-XXXXX
5. Disconnect the vacuum hose (D) from the EVAP
canister vent shut valve (E), and connect a vacuum
pump to the vacuum hose.
6. Pump the vacuum pump 80 times.
. lf the vacuum holds, goto steP 7.. lf the vacuum does no1 hold, go to step 10.
(cont'd)
11-187

Fuel Fill Door Opener Replacement
1.Using a flat-tip screwdriver wrapped with
protective tape, detach the hooks (A) by prying the
front side cap (B), then remove it from the left door
silltrim (C), and loosen the bolt (D) securing the
fuel fill door opener.
6x1.0mm9.8 N.m11.0 kgf m,7.2 lbf.ft)
Remove the left door sill trim (see page 20-50i.
Remove the opener (Alfrom the bolt {B).
2.
3.
4. Disconnect the fuel fill door opener cable (A), then
remove the opener iB). Take care not to bend the
ca o te.
Installthe opener in the reverse order of removal,
and note these items:
5.
lMake sure the opener cable is connected
properly.
lvlake sure the fuel fill door opens properly and
locks securely.
20-109