2002 HONDA CIVIC Fuel

DTC Troubleshooting
DTC P0451: FTP Sensor Range/Performa nce
Problem
Special Tools Required
Vacuum Pump/Gauge, 0-30 in. Hg A973X-041-XXXXX
1. Remove the fuel fill cap.
2. Turn the ignition switch ON (ll)
3. l\4onitor fuel tank pressure (FTP) sensorvoltage
with the Honda PGM Tester, or medsure voltage
between ECM connectorterminals E4 and E14.
ECM CONNECTOR E 131P)
Wire side of female terminals
ls there about 2.5V?
YES-Go to step 4.
NO Replace the FTP sensor.I
Turn the ignition switch OFF.
Disconnect the hose between the EVAP two way
valve and the FTP sensor at the EVAP two way
valve end.
4.
5.
7.
8.
6. Connect a vacuum pump to the open end of the
hose.
Turn the ignition switch ON {ll).
l\4onitor FTP sensor voltage with the Honds PGM
Tester, or measure voltage between ECM
connector terminals E4 and E14, and carefully
squeeze the vacuum pump a little.
ECM CONNECTOR E 13lPI
Wire side of lemale terminals
The voltage should smoothly drop from about 2.5 V
to about 1.5 V. Stop applying vacuum when the
voltage drops to about 1.5 V or damage to the FTP
sensor may occur.
Does the voltage drop to about 1.5 V and hold?
YES Check for misrouted, leaking, or broken FTP
sensor vacuum lines. lf the vacuum lines are OK,
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 ECM, replace the
original ECM.I
NO Replace the FTP sensor. !
9.
11-171

EVAP System
DTC Troubleshooting (cont'd)
DTC P0452: FTP Sensor Circuit Low Voltage
1. Check the vacuum lines at the FTP sensor for
misrouting, leakage. breakage, or clogging.
Are the vacuum lines OK?
YES Go to step 2.
NO Repair or replace vacuum lines as
necessary. I
2. Reset the ECM (see page 11-4).
3. Remove the fuelfill cap.
4. Turn the ignition switch ON (ll)
5. Monitor FTP sensor voltage with the Honda PGM
Tester, or measure voltage between body ground
and ECM connector terminal E14.
ECM CONNECTOR E 131PI
1 2t3t45o/89
././114tc61./182C21
22123241 t26271/ 2931
TP (LT GRN)
Wire side of female terminals
ls thete about 2.5 V?
YES- Intermittent failure, system is OK at this time.
Check for poor connections or loose terminals at
the FTP sensor and at the ECrM.l
NO Go to step 6.
11-172
6. Turn the ignition switch OFF.
7. Reinstallthe fuel fill cap.
8. Disconnect the FTP sensor 3P connector.
9. Turn the ignition switch ON (ll)
10. Measure voltage between FTP sensor 3P connector
terminals No. 1 and No.2.
FUEL TANK PRESSURE SENSOR 3P CONNECTOR
VCgl {YEL/BLU}
Wire side of female terminals
ls there about 5 V?
YES Go to step 1 '1.
NO-Repair open in the wire between the FTP
sensor and the ECM {E5).1

't2.
13.
14.
11. Measure voltage between FTP sensor 3P connector
terminals No. 2 and No.3.
FUELTANK PRESSUBE SENSOR 3P CONNECTOR
FTP (LT GBN)
Wire side of femaleterminals
ls there about 5 V?
YES - Replace the FTP sensor. t
NO-Go to step 12.
Turn the ignition switch OFF.
Disconnect ECM connector E (31P),
Check for continuity between FTP sensor 3P
connector terminal No. 3 and body ground.
FTP SENSOR 3P CONNECTOB
FTP (LT GRNI
Wire side of femalelerminats
ls there continuity?
YES Repair short in the wire between the FTP
sensor and the ECI\4 {E14).I
NO-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/indicationgoes away with a known-good EClvl, replace the
original ECM.I
DTC P0453: FTP Sensor Circuit High Voltage
1. Check the vacuum lines at the FTP sensor for
misrouting, leakage, breakage, or clogging.
Are the vacuum lines OK?
YES-Go to step 2.
NO Repair or replace vacuum lines as
necessary.I
2. Reset the ECM {see page 11'4).
3. Remove the fuel fill cap.
4. Turn the ignition switch ON (ll).
5. lvlonitor FTP sensor voltage with the Honda PGM
Tester, or measure voltage between body ground
and ECM connector terminal E'14.
ECM CONNECTOR E 131PI
112134567I9
56/ t182C21
242il./29 3031
TP {LT GRN}
Wire side of female terminals
Is there about 2.5 V?
YES Intermittent failure, system is OK at this time.
Check for poor connections or loose terminals at
the FTP sensor and at the ECM.I
NO Go to step 6.
{cont'd)
11-173

EVAP System
DTC Troubleshooting (cont'dl
6. Turn the ignition switch OFF.
7. Reinstall lhe fuel fill cap.
8. Disconnect the FTP sensor 3P connector.
9. Turn the ignition switch ON (ll).
'10. l\4easure voltage between FTP sensor 3P connector
terminals No. 1 and No.2.
FTP SENSOR 3P CONNECTOR
VCC3 (YEL/BLU)
Wire side of female terminals
ls there about 5 V?
YES Go to step 11.
NO-Repair open in the wire between the FTP
sensor and the ECM (E4). !
11-174
11, Measure voltage between FTP sensor 3P connector
terminals No.2 and No.3.
FTP SENSOR 3P CONNECTOR
FTP ILT GRN}
Wire side of female terminals
ls there about 5 V?
YES Replace the FTP sensor.l
NO Go to step 12.
l\4easure voltage between ECM connector
terminals E4 and E 14,
ECM CONNECTOR E (31P)
Wire side of female terminals
ls there about 5 V?
YES Repair open in the wire between the FTP
sensor and the ECM (E14).I
NO Update the ECM if it does not have the latest
software, or substitute a known-good ECN4. then
recheck (see page 11-6). lf the symptom/indication
goes away with a known-good ECM, replace the
original ECM.I
\

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

EVAP System
DTC Troubleshooting (cont'dl
20. Plug the fueltank port (A) oftheEVAPtwoway
valve,
While monitoring FTP sensor voltage with the
Honda PGM Tester, or measuring the voltage
between ECM connector terminals E4 and E 14,
slowly pump the vacuum pump until the voitage
droDS to about 1.5 volts.
ECM CONNECTOR E {31PI
Wire side of female terminals
Does the voltage dtop to 1.5 V and hold fot at
Ieast 20 seconds?
YES-The EVAP bypass solenoid valve/EVAP two
way valve is OK. Go to step 22.
NO Repair the leak from the EVAP bypass
solenoid valve, EVAP two way valve. or
FTP sensor.l
11-178
Wire side of female terminals
EVAP Canister Vent Shut Valve Test
22. Disconnect the vacuum hose from the EVAP
canister vent filter (A), and connect a vacuum pump
to the hose.
Turn the ignitlon switch ON (ll).
Apply vacuum to the hose with five strokes of the
pump.
Does the valve hold vacuum?
YES Go to step 25.
NO The EVAP canister vent shut valve is OK. Go
to step 30.
Turn the ignition switch OFF.
Disconnect the EVAP canister vent shut valve 2P
conneclor.
Check for continuity between EVAP canister vent
shut valve 2P connector terminal No. 2 and body
ground.
EVAP CANISTEB VENT SHUTVALVE 2P CONNECTOR
{LT GRN/REOI
\
25.
26.
21.

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
DTC Troubleshooting (cont'd)
DTC Pl457: EVAP Control System(EVAP Canister 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 system failure.
SpecialTools 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, certain specific driving
and ambient conditions must occur before the ECfM will
complete the system checks, Additional test drives may
still not meet the specific conditions needed to16^r^.1' '^6 rh6 ^^.16
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 lhat creates
greater pressure/vacuum. The optimum condition for
testing is fresh fuel, and there must be less than a full
tank. lf possible, to assist in leak detection, add I gallon
of fresh fuel to the tank (as long as it will not fill the
tank), just before starting these procedures.
EVAP Canister Purge Valve Test
1. Disconnect the vacuum hose from the EVAP
canister purge valve (A), and connect a vacuumpump to the hose.
11-180
4973X-041-XXXXX
ECM CONNECTOR A I24P'
Wire side of lemale terminals
4.
7.
2. Turn the EVAP canister purge valve on with the
Honda PGM Tester, or connect ECM connector
terminal 821 to body ground with a jumper wire.
Turn the ignition switch ON (ll).
Apply vacuum to the hose.
Does the valve hold vacuum?
YES-Go to step 5.
NO-The EVAP canister purge valve is OK. Go to
step 10.
Turn the ignition switch OFF.
Disconnect the EVAP canister purge valve 2P
conneclor,
Check for continuity between EVAP canister purge
valve 2P connector terminal No. 2 and body ground.
EVAPCANISTEN PURG€VALVE 2P CONNECTOR
-4-
lll2l-fircs
IYEL/8Lu)(f])
I
Wire side offemale lerminals
ls there continuity?
YES-Go to step 8.
NO Repair open in the wire between the EVAP
canister purge valve and the ECM/PCM (821).I
Turn the ignition switch ON (ll).
t
b.
8.