2003 HONDA CIVIC engine

FuelSupply System
Fuel Pressure Relieving
Before disconnecting fuel lines or hoses, relieve
pressure from the system by disconnecting the fuel
tube/quick connect fitting in the engine compartment.
1. Turn the ignition switch OFF,
2. Remove the PGM-Fl main relay 2 (A).
Startthe engine, and let it idle until it is stalls.
NOTE: The DTCS or Temporary DTCS P0301. P0302,
P0303, P0304 may come on during this procedure.
lf any DTCS are stored, ignore them.
Turn the ignition switch OFF.
Remove the fuel fill cap, and relieve fuel pressure
in the fueltank.
Remove the engine cover.
Disconnect the negative cable from the battery.
Check the fuel quick-connect fitting for dirt, and
clean it if necessary.
3.
4.
6.
7.
8.
11-144
11
10.
9. Place a rag or shop towel over the quick-connect
fitting (A).
Disconnect the quick-connect fifting (A): Hold the
connector (B) with one hand and squeeze the
retainer tabs (C) with the other hand to release
them from the locking pawls {D). Pullthe connector
off.
NOTE:. Prevent the remaining fuel in the fuel feedlineor
hose from flowing out with a rag or shop towel.. Be careful notto damage the line (E) or other
pa rts.. Do not use tools.. lf theconnectordoes not move, keepthe retainer
tabs pressed down, and alternately pull and push
the connector until it comes off easily.. Do not remove the retainer from the line; once
removed, the retainer must be replaced with a
new one.
After disconnecting the quick-connect fifting, check
it for dirt or damage (see page 1 1-149).

Fuel Pressure Test
Special Tools Required. Fuel pressure gauge 07406-0040004. Fuel pressure gauge sel 07ZAJ-S5A0100
1. Relieve the fuel pressure (see page 1'1-144).
2. Disconnect the quick-connect fitting (A). Aftach the
fuel pressure gauge set and fuel pressure gauge.
Start the engine and let it idle.
. lf the engine starts, goto step 5.. lf the engine does not start, goto step 4.
Check to see if the fuel pump is running: listen to
the fuel fill port with the fuel fill cap removed. The
fuel pump should run for 2 seconds when the
ignition switch is first turned on.
. lf the pump runs, go to step 5.. lf the pump does not run, do the fuel pump circuit
troubleshooting (see page 1 1-1 41 ).
Read the pressure gauge. The pressure should be
320-370 kpa (3.3-3.8 kgf/cm', a7-52 psi)
. lf the pressure is OK, the test is complete.. lf the pressure is out of specification, replace the
fuel pressure regulator and the fuel filter (see
page 11-152), then recheck the fuel pressure.
5.
11-145

4. Align the quick-connect fittings with the line (A).
and align the retainer (B) locking pawls with the
connector {C) grooves. Then press the quick-
connect fittings onto the line until both retainer
pawls lock with a clicking sound.
NOTE; lf it is hard to connect, put a small amount of
new engine oil on the line end.
Connection with new retainer:
Reconnection to existing retainer:
5. lvlake sure the connection is secure and that the
pawls are firmly locked into place; check visually
and by pulling the connector.
6. Reconnectthe negative cable to the battery, and
turn the ignition switch ON (ll). The fuel pump will
run for about 2 seconds, and fuel pressure will rise
Repeat 2 or 3 times, and check that there are no
fuel leaks.
11-151

Fuel Supply System
Fuel Pulsation Damper Replacement
1. Relieve the fuel pressure(seepagell-144).
2. Remove the engine cover.
3. Remove the fuel rail mounting nuts from the fuelrail.
4. Remove the ground cable (G 101.
5. Raise the fuel rail.
6. Place awrench (A) onthefuel rail (B).
7. Place a wrench (C) onthefuel pulsation damper (D).
8. Remove the pulsation damper.
9. Installthe fuel pulsation damper in lhe reverse
order of removal with new washers.
NOTE:. Replace all washers wheneve r the fuel pulsation
damper is loosened or removed,. lf the drain hole (A) ofthefuel pulsationdamper
cover does not face bottom, reinstall it as shown.
11-154

Intake Air System
Throttle Body Test
NOTE:. Do not adjust the throttle stop screw. lt is preset at the
factory.. lf the malfunction indicator lamp (MlL) has been
reported on, check for diagnostic trouble codes(DLCS) (see page 11 3).
1. With the engine off, check the throttle cable
movement. The cable should move without binding
or sticking.
. lf lhe cable moves OK, goto step 2.. lf the cable binds or sticks, check it and its routing.. lf the cable isfaulty, reroute itor replace itand
adjust it (see page 11-163), then go to step 2.
2. l\4ove the throttle lever by hand to see if the throftle
valve and/or shaft are too loose or too tight.
. lf there is excessive play in the throttle valve
shaft, or any binding in the throttle valve at the
fully closed position, replace the throttle body.. lf thethrottlevalve and shaft are OK, goto step3.
3. Connect the scan toolto the DLC.
Turn the ignition switch ON (ll).
Check the throttle position with the scan tool. The
reading should be about 10% when the throttle is
fully closed and about 90% when the throttle is fully
openeo.
. lf the throttle position is correct, the throttle body
is OK.. lf thethrottle position is notcorrect, replace the
throttle body.
5.
11-160
!

Intake Air Bypass GontrolThermalValve Test
Special Tools Required
Vacuum Pump/Gauge,0 30 in. Hg A973X-041-XXXXX
1. Stan the engine. Then let it idl€.
NOTE: The engine coolant temperature must be
below 149'F (65'C).
2. Remove the vacuum hose (A)from the intake air
duct, and connect a vacuum pump/gauge to the
nose.
3. Raise and lowerthe engine speed. and make sure
the vacuum gauge reading changes as the engine
speeo cnanges.
lf the vacuum reading does not change, check for
these problems:
. Misrouted, leaking, broken, or clogged intake air
bypass control system vacuum lines.. A cracked or damaged intake air bypass control
thermal valve.
4. Hold the engine at 3,000 rpm with no load (in
neutral) until the radiator fan comes on, then let it
id le.
5. Raise and lower the engine speed, and make sure
the vacuum gauge reading does not change as the
rpm cnanges.
lf the vacuum reading changes, check for these
proorems:
. l\4isrouted, leaking, broken, or clogged intake air
bypass control system vacuum lines.. A cracked or damaged intake air bypass control
thermal valve.
11-161

Intake Air System
Throttle Cable Removal/lnstallation
1. Fully open the throttle valve, then remove the
throttle cable (A) from the throttle link (B).
Remove the cable housing (C)from the cable
bracket (D).
Remove the throttle cable (A)from the accelerator
pedal (B).
2.
3.
SILICONE GREASE B(P/N 08798-9002)
(P/N 08?98-9002)
11-164
5.
Install in the reverse order of removal.
After installing, start the engine. Hold the engine at
3,000 rpm with no load (in neutral) untilthe radiator
fan comes on, then let it idle.
Hold the cable, removing all slack from it.
Set the locknut on the cable bracket {A).Turn the adjusting nut (B) so that its free play is
0 mm.
The should beno crearance.
Remove the cable from the cable bracket (A). Set
the adjusting nut on the other side of the throttle
bracket, then tighten the locknut {C}.
With the cable properly adjusted, check the throttle
valve to be sure it opens fully when you push the
accelerator pedal to the floor. Also check the
throttle valve to be sure it returns to the idle
position whenever you release the accelerator
Deoat.
7.
!
8.
9.
('1.0 kgf.m,7.2 tbf.ftl

Catalytic Converter System
DTC Troubleshooting
DTC P0420: Catalytic System Efficiency
Below Threshold
NOTE: lf some of the DTCS listed below are stored at
the same time as DTC P0420, troubleshoot those DTCS
first, then recheck for DTC P0420.
P0137, P0138: Secondary Heated Oxygen Sensor(secondary HO2S) (Sensor 2)
P0141: Secondary HO2S (Sensor 2) heater
1. Reset the ECM {see page 1'l-4}, then continue to
step 2 through 5 to reset the readiness code.
2. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) untilthe radiator fan comes on.
Drive for about l0 minutes without stopping. Your
speeo can vary.
With the transmission in 4th gear, drive at a steady
speed between 50 62 mph (80-'100 km/h) for
30 seconds.
Repeat step 4 three times. Between each repetition,
close the throttle completely for 1 2 seconds. lf
the engine is stopped during this part of the
procedure, repeat steps 3, 4 and 5.
Check for a Temporary DTC with the scan tool.
Does the scan tool indicate Temporaty DTC
P0420?
YES Check the TWC. lf necessary, replace the
TWC.I
NO Check for readiness code completion. lfthe
readiness is complete, it was a interminent failure,
and the system is OK at this time. lf the readiness
code is incomplete, repeat steps 2 through 5.1
4.
11-167