2003 HONDA CIVIC ECT sensor

Evaporative Emission (EVAPI Control
System
Refer to the System Diagram to see the functional
layout of the system.
EVAP Canister
The EVAP canister temporarily stores fuel vapor from
the fuel tank until it can be purged back into the engine
and burned.
EVAP Canister Purge Valve
When the engine coolant temperatu re is below 149'F(65'C), the ECM turns off the EVAP canister purge valve
which cuts vacuum to the EVAP canister.
FuelTank Pressure (FTP) Sensor
The FTP sensor converts fueltank absolute pressure
into an electrical inputto the ECM during the EVAP leak
cnecK.
SENSOR UNIT
EVAP Two Way Valve and EVAP Eyp8s Solenoid
Valve
The EVAP two way valve is installed between the fuel
tank and the EVAP canister line.
The EVAP two way valve sends fuel vapor to the EVAP
canister corresponding to the pressure inside the tuel
tank. lt also relieves excess vacuum in the tank by
allowing fresh air to be drawn into the tank through the
EVAP canister.
The EVAP bypass solenoid valve opens to bypass the
two way valve during the EVAP leak check.
EVAP BYPASSSOLENOID VALVE
VALVE
(cont'd)
To FUEL TANK
11-35

Fuel and Emissions Systems
I
a
a
System Descriptions (cont'd)
ECM Circuit Diagram
CONNECTOi
mrrrrn
CMP SENSOR B(TDC SENSOn)
I-BRN/YEr-
11-38
\,

Fuel and Emissions Systems
System Descriptions (cont'dl
ECM Circuit Diagram {cont'd)
\
-{ffi]---1t-|
IATSENSOR
-{El------l
ECTSENSOS
T_""",,..
I-BFN/YEL
ft^--l
,","., J t-|':I REVERSEI LocKI soleloto+ vaLvE
t!j]]
CMPSENSOAA
L-IJUNCTIONI CONNECTOR
-
11-40

Fuel and Emissions Systems
How to Set Readiness Codes
Malfunction lndicator Lamp (MlL) Indication
(ln relation to Readiness Codesl
The vehicle has certain "readiness codes" that are part
of the on-board diagnostics for the emissions systems.
lf the vehicle's battery has been disconnected or gone
dead, if the DTCS have been cleared, or if the ECM has
been reset, these codes are set to incomplete. In some
states, part of the emission testing is to make su re these
codes are set to complete. lf all of them are not set to
complete, the vehicle may fail the emission test, or the
test cannot be finished.
To check ifthe readiness codes are complete, turn the
ignition switch ON (ll), but do not start the engine. The
MIL will come on for 15 20 seconds. lf it then goes off,
the readiness codes are complete. lf it blinks several
times, one or more readiness codes are not complete.
To set readlness codes from incomplete to complete.
do the procedure for the appropriate code.
11-46
L
Catalytic Converter Monitor and Readiness
Code
NOTE:. Do not turn the ignition switch off during the
procedure.
. All readiness codes are cleared when the battery is
disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PG lvl Tester.. Low ambient temperatures or excessive slop-and-go
traffic may increase the drive time needed to switch
the readiness code from incomplete to complete.' The readiness code will not switch to com Dlete until
all the enable criteria are met.. lf a fault in the secondary HO2S system caused the
MIL to come on. the readiness code cannot be set to
comDlete until vou correct the fault.
Enable Criteria. ECT at 158"F (70'C) or higher.. Intake air temperature (lAT) at 20"F (-7'C) or higher.. Vehicle speed is steady, and vehicle speed sensor
(VSS) reads more then 25 mph (13km/h).
Procedure
1. Connect the scan tool to the vehicle's data link \
connector (DLCi, and bring up the tool's generic \"
OBD ll mode.
Start the engine.
Test-drive the vehicle under stop-and-go conditions
with short periods of steady cruise. After about
5 miles (3 km), the readiness code should switch
from incomplete to complete.
lf the readiness code is still set to incomplete, check
for a temporary DTC. lf there is no DTC, one or
more of the enable crlteria were probably not met;
2.
3.

Evaporative Emissions (EVAP) Control
System Monitor and Readiness code
NOTE:
All readiness code are cleared when the batterV is
disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PGM Tester.
The enable criteria must be repeated if the intake air
temperature (lAT) drops lower than 36'F (20"C) from
its value at engine $an up.
Enable Criteria
At engine start up, ECT and IAT are higher than 32'F(0"C) , but lower than 95'F (35"C).
At engine start up, the ECT and IAT are within 12'F(7'C) of each other.
Procedure
1. Connect the scan tool to the vehicle's data link
connector (DLC), and bring up the tool's generic
OBD ll mode.
2. Start the engine.
3. Test-drive the vehicle under stop-and-go conditions
with short periods of steady cruise. After about
2.5 miles (1.6 km), the readiness code should
switch f rom incomplete to complete.
4. lf the readinesscode isstill setto incomplete, check
for a temporary DTC. lf there is no DTC, one or
more of the enable criteria were probably not met;
repeat the procedure.
Air Fuel Ratio (A/Fl Sensor Monitor and
Readiness Code
NOTE:. Do not turn the ignition switch off during the
orocedure.. All readiness codes are cleared when the baftery is
disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PGM Tester.
Enable Criteria
ECT at 140'F (60"C) or higher.
Procedure
1. Connect the scan toolto the vehicle's data link
connector (DLC), and bring up the tool's generic
OBD ll mode.
2. Start the engine.
3. Test-drive the vehicle under stop-and-go conditions
with short periods of steady cruise. During the
drive, decelerate (wirh the throttle fully closed) for
5 seconds. After about 3.5 miles (2.2 km). the
readiness code should switch from incomDlete to
complete.
4. lfthereadinesscodeisstill set to incomplete, check
for a temporary DTC. lfthere is no DTC, the enable
criteria was probably not meU repeat the procedure.
Air/Fuel Ratio (A/Fl Sensor Heater Monitor
Readiness Code
NOTE; All readiness codes are cleared when the battery
is disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PGM Tester,
Procedure'1. Connect the scan tool to the vehicle's data link
connector {DLC), and bring up the tool's generic
OBD ll mode.
2. Start the engine, and let it idle for 1 minute. The
readiness code should switch from incomplete to
comDlete.
3. lf the readiness code is still set to incomplete, check
for a temporary DTC. lf there is no DTC, repeat theproceoure.
(cont'd)
11-47

PGM-FI System
Component Location Index
CAMSHAFT POS]TION {CMP) SENSOR B(TOP DEAD CENTER (TDC}SENSORITroubleshootina. oaoe 1 1-95Replacement, p;ge 1-1.1 14
ELECTRICAL LOADDETECTOR {ELDITroubleshooting,page 1'l -92
INTAKE AIR TEMPERATURE{IATI SENSORTroubleshooting,page 'l'l-55
Replacement, page 11-'l 15
f- \
rl
KNOCK SENSORTroubleshooting, page 1 1-77Beplacement, page 11 115
ENGINE COOLANT TEMPERATURE(ECTI SENSORTroubleshooting, page 1 1-57Replacement, page 11 114
MANIFOLD ABSOLUTE PRESSURE(MAP) SENSORTroubleshooting, page 1 1-52
THROTTLE POSITIONITP} SENSORTroubleshooting, page 11-60CRANKSHAFT POSITIONICKPISENSORTroubleshooting, page'l 1-78Beplacement, page 1 1-'l 16
AIR FUEL RATIO {A/F)SENSOR ISENSOR 1}Trorrbleshooting, page 1 1-84Replacement, page 11- 1 13
{cont'd)
ii'- r'1
.I11 ---:,I''.!,i(..,.?:fir-J-
.....,..:--.
11-49

PGM-FI System
(
(
(
DTC Troubleshooting
DTC P0107: MAP Sensor Circuit Low Voltage
1. Turn the ignition switch ON (lli.
2. Check the MAP with the scan tool.
ls about 101 kPa (760 mmHg,30 in.Hg)or 2.9 V
indicated?
YES Intermittent failu re, system is OK at this time.
Check for poor connections or loose terminals at
the MAP sensor and at the ECM.I
NO-Go to step 3.
3. Turn the ignition switch OFF.
4. Disconnect the MAP sensor 3P connector.
5. Turn the ignition switch ON (lll.
6. lvleasure voltage between MAP sensor 3P
conneclor terminals No. 1 and No. 3.
1.
sGl{GRN/WHTI
Wire s de of femaleterminais
ls there about 5 V?
YES Go to step 8.
NO-Go to step 7.
Measure voltage between EClvl connector
terminals 41 1 and 42'1.
ECM CONNECTOR A 13'IP}
MAP SENSOR 3P CONNECTOF
vccr{YEL/BED)
sGr{GRN/WHT}
11-52
Wire side of female terminals
\
8.
ls there about 5 V?
YES-Repair open in the wire between the Eclvl(A21)and the MAP sensor.l
NO Update the ECM if it does not have the latest
software, or substitule a known-good ECM, then
recheck (see page 'l 1-6). lf the symptom/indication
goes away with a known-good ECfvl, replace the
original ECM.I
Check the MAP with the scan tool.
ls 2 kPa (15 mmHg,0.6 in.Hg) ot less or 0 V
ind icated?
YES-Go to step 9.
NO Replace the lvlAP sensor.l
Turn the ignition switch OFF.
Disconnect ECM connector A (31P).
Check for continuity between MAP sensor
connector terminal No. 2 and body ground.
MAP SENSON 3P CONNECTOA
ls therc continuity?
YES-Repair short in the wire between the ECM(A19) and the MAP sensor.l
NO Update the ECM if it does not have the latest
software, 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
9.
'10.
11.
\

DTC P0108: MAP Sensor Circuit High Voltage
'1. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) until the radiator fan comes on,
then let it idle.
2. Check the MAP with the scan tool.
le about 101 kPa (780 nmHg, 30 in.Hg) ot highet,
or about 2.9 V or higher indicated?
YES Go to step 3.
NO-lntermittent failure, system is OK at this time.
Check for poor connections or loose terminals at
the MAP sensor and at the ECM.I
3. Turn the ignition switch OFF.
4. Disconnectthe MAP sensor 3P connector.
5, Connect MAP sensor 3P connector terminals No. 2
and No. 3 with a jumper wire.
MAP S€NSOR 3P CONNECTOR
MAP{GRN/REO}SG1 (GRN/WHTI
JUMPER WIRE
Wire side of female terminals
6. Turn the ignition switch ON (ll).
7. Check the MAP with the scan tool.
ls about 101 kPa (760 mmHg,30 in.Hg) ot higher,
or about 2.9 V or higher indicated?
YES-Go to step 8.
NO Replace the MAP sensor.I
8. Remove the jumper wire.
123
9. Measure voltage between MAP sensor 3P
connector terminals No. 1 and No. 3.
MAP SENSOR 3PCONNECTOF
vccl{YEL/RED) l,lo cll.l.rl
I lsct
d) l{GRN/wHrr
YIilll
Wire side of female lerminals
ls there about 5 V?
YES Go to step 10.
NO Repair open in the wire between the ECM
(A1 1 ) and the MAP sensor.I
Turn the ignition switch OFF.
Connect ECM connector terminals A11 and A19
with a jumper wire.
ECM CONNECTOR A {31PI
Wire side of fema e te.minals
Turn the ignition switch ON (ll).
Check the MAP with the scan tool.
ls about 101 kPa (760 mmHg, 30 in.Hg) or higher,
or about 2.9 V ot higher indicated?
YES Update the ECM if it does not have the lalest
software, or substitute a known-good ECM, lhen
recheck (see page 1 1-6). lf the symptom/indication
goes away with a known good ECM, replace the
original ECM.I
NO-Repair open in the wire betlveen the ECI\il
(A19) and the MAP sensor.I
10.
11.
JUMPER WIAE
11-53