1997 HONDA CIVIC engine code

ldle Control System
ldle Air Control (lAC) Valve ('96 - 98 A/T and Dl6Y7 enginel
The (Rotary) IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from theECM/PCM in order to maintain the proper idle speed,
BIMETAL
VALVESTOPPER
1P1509 Thescantool indicates Diagnostic Trouble Code (DTC) P1509: A problem in the idle Air Control (tAC)valve circuit.
ECM/PCM CONNECTOR A I32PIPGl IBLKI
IAC VALVE 3P CONNECIOR
IACV NIACV P
IGP
Terminal side of maleterminals
*: IACV N line
1 1-198
The MIL has b€€n roported on.DTC P1509 is stored.
Problem verification:1. Do the ECM/PCM Reset Proce-oure.2. Turn the ignition switch ON (ll).
Intermittent failura, systom ia OKat this time. Check tor poo. con-noctions or loose wires at C109llAC valve) and ECM/PCM.
ls DTC P1509 indicated?
Check for an opon in the wirer{PG lines):Measure voltage between bodvground and ECM/PCII connectorterminals A10 and A23 individu
Repair op€n in the wires betwoenECM/PCM and G101 llocated attho thermostat housing).
ls there more than 1.0 V?
Chock th€ ECM/PCM inpui volt-agel1. Turn the ignition switch OFF.2. Disconnect ECM/PCM connec-tor A (32P)from the ECM/PCM.3. Turn the ignition switch ON (ll).4. Measu re voltage betweenbody ground and ECM/PCMconnector terminals A14 andA13* individually.
Ch6ck th6 IAC valve:1. Turn the ignition switch OFF.2. Disconnect the IAC valve 3Pconnector,3, Measure resistance betweenIAC valve 3P connector termi-nal No.2 and terminals No. 1and 3 individually.
ls there 16 - 28 g?
Substitute a known-good ECM/PCM and recheck. lf symptom/indication goos away, replaceth€ origin.l ECM/PCM.
SHAFT
rAcv N loRNl*
(To page 11-199)
Wire side of lemale terminals
123a56El011
121314r5161718t9202:22321
272AA30
IACV P {BLK/BLUI

ldle Gontrol System
The (Rotary) IAC Valve changes the amount of air bypassing the throttle body in response to a current signal from the
ECM/PCM in order to maintain the proper idle speed.BIMETALHOLDER
BIMETAL
SHAFTVALVESTOPPER
ECM/PCM CONNECTOR B {25P}
(To page 11-201)
IAC VALVE 3P CONNECTOR
IACV NIACV P
ldle Air Control {lACl Valve ('99 - 00 A/T and Dl6Y7 enginel
YES
1P1509 lThescantool indicates Diagnostic Trouble Code (DTC) P1509:A problem inthe idleAirControl (lAC)valve circuit.
IGP
Terminal side of maleterminals
Sub3titute e known-good ECM/PCM .nd recheck. lf 3vmptom/indicalion goos away, replac6thc original ECM/PCM.
*: IACV N line
11-200
Tho MIL has b€en reported on.OTC P1509 is sto.ed.
Problem verilicationr1. Do the ECM/PCM Reset Proce-dure.2. Turn the ignition switch ON (ll).
Intermittont tailure, sy3tem i3 OKat thb time. Check for poor con'noctions or loose wiros at C109(lAC velvel and ECM/PCM.
ls DTC P1509 indicated?
Check for an oDen in the wilosIPG linesl:Measure voltage between bodyground and ECM/PCM connectorterminals 82 and 810 individually.
Ropail open in the wires be'tw€enECM/PCM .nd G101 llocated .tthe the.mostat housingl.ls there more than 1.0 V?
Check tho ECM/PCM input volt-age:1. Turn the ignition switch OFF.2. Disconnect ECM/PCM connec-tor A (32P)trom the ECM/PCM.3. Turn the ignition switch ON (ll).
4, Measure voltage betweenbody ground and ECM/PCMconnector terminals 86 and815* individually.
Chock the IAC v.lve:1. Turn the ignition sw;tch OFF.2. Disconnect the IAC valve 3Pconnoctor.3. Measure resistance betweenIAC valve 3P connector termi'nal No. 2 and terminals No. 1and 3 individually.
ls there 16 - 28 O?
Wire side of female terminals

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lTo420l Th" """n toot indicates Diagnostic Troubte code (DTc) p0420: catatyst sysrem efficiency below threshold.
Description
This system evaluates the catalyst's capacity by means of the Ho2s {Primary and secondary) output during stable driving
conditions. ll deterioration has been detected during two consecutive driving cycles. the MIL comes on and DTC P0420 will
be stored.
NOTE: lf some of the DTCS tisted below are stored at the same time as DTC P0420, troubleshoot those DTCS first. then
recheck for DTC P0420
P0137, P0138: Secondary HO2S (Sensor 2)
Po14'1:Secondary H02S {Sensor 2) Heater
Possibl€ Cause
. TWC Deterioration
. Exhaust system leakage
Troubleshooting Flowchart
I
The MIL has been reported on.
DTC P0420 is stored
Problem verilication:1. Do the ECM/PCM Reset Proce
dure.2. Start the engine Hold the
engine at 3,000 rpm wath no
load {in Park or neutral) until
the radiator fan comes on.
3. Connect the SCS service con
4. Test drive 40 - 55 mph for
approx, two minutes Then
decelerate for at least 3 sec_
onds with the throttle com'pletely closed- Then reduce
the vehicle speed to 35 mph,
and try to hold it until the
readiness code comes on
Intermittent Iailure, system is OK
at this time.ls DTC P0420 indicated?
Check the TWC {see section 9l
lf necessary, replace the TwC

Emission Control System
Exhaust Gas Recirculation (EGR) System (D16Y5 engine with GWI (cont'dl
lTl49il T_he scan tool indicates Diagnostic Trouble Code (OTC) P1491: A malfunction in the Exhaust Gas Recirculation- lEgh) svstem.
CvT lM/T see page 1l-2611:
J
EGR VALVELIFT SENSOR#16 HOSE
PUMP/GAUGE,0- 30 in.HsA973X-041-XXXXX
EGRVALVE
The MIL has been reoorted on.DTC P1491 is stoled.
Problem verification:1. Do the ECM/PCM Reset Proce-du re.2. Connect the SCS service con'
3. Start the engine. Hold theengine at 3,000 rpm with noload {in Park or neutral) untilthe radiator fan comes on,4. Drive the vehicle on the roadfor approx. 10 minutes. Try tokeep the engine speed in the1,700 - 2,500 rpm range.
Intermittonl failure, system is OKat this time. Check for Door con-nections or loose wires at, C144{EGR velve} and ECM/PCM.
ls DTC P l49l indicated?
Check fo. vacuum to ihe EGR
1. Disconnect the No. 16 hose fromthe EGR valve.2. Connect a vacuum pump/gauge to the hose.3. Start the engine and let it idle.
ls there any vacuum?
Check tor a malfunction in theEGR control solenoid valve:'1. Disconnect the EGR controlsolenoid valve 2P connector,2. Becheck the No. 16 hose for
Check vacuum hose routing o,the entire EGR svstem. lf hoserouting is OK, replac€ the EGRcontrol solenoidvalv6.
ls there any vacuum?
Substitute a known-good ECM/PCM and recheck. It symptom/indicalion goes away, replacethe original ECM/PCM.
(To page 11 257)
11-256

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Exhaust Gas Recirculation System
The scan tool indicates Diagnostic Trouble
Recirculation (EGRlvalve lift sensor circuit.
(D16Y5 enginel
Code {DTC) P1498: A high voltage problem in the Exhaust Gas
EGR VALVE LlFf SENSOR 3P {M/T: 6Pl CONNECTOR (C1441
cvT:
vcc2{YEL/BLUI
SG2 IGRN/BLK)
IM/T:sG2{GRN/BLKI
Wir€ side ol lemale terminals
ECM CONNECTOR D (16P)
vcc2(YEL/BLUIsG2(GRN/BLK)
Wir€ side of female terminals
PCM CONNECTORS C 131P)'
Wire side oI female terminals
11-265
- The MIL has been reportod on.- DTC P1498 is storod.
Probl€m verification:1. Do the ECM/PCM Reset Proce
dure.2. Stan the engine.
Intermittent tailure, sy3lem is OK
at lhis time. Check tor poor con'
nections or loose wire3 at C144
|EGR valvel and ECM/PCM.
ls DTC P1498 indicated?
Check for an open in tho EGRvalv6 lift sen3or:1. Turn the ignition switch OFF.
2. Disconnect the EGR valve lift
sensor 3P (M/T: 6Pl connector.
3. Turn the ignition switch ON (ll).
4. Measure voltage between the
EGR valve litt sensor 3P lM/T:6P) connector terminals No. 3and No.2.
ls there approx.5 V?
Check lor op€n in th€ wire (SG2
line):Measure voltage between ECM/PCM connector terminals 010 andD1l (C18 and C28)*.
Repair open in tho wiro betwoen
ECM/PCM lDl1 (Cl8)r) and EGR
valvo lift sensor.ls there approx. 5 V?
Substitute . known-good ECM/PCM and recheck. ll symptom/indicrtion goes away, replacothe original ECM/rcM.
*:'99 - 00 D16Y5 engine with CVT

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,96 D16Y5 engine,,96 D16r,gngino,,96 Dt6Y8 engine {3edan)' 37 D16Y5 engino..97 D16r, engine {coupe: KA, Kc mod-
els. sedan: KA, KC, KL {DX} models. hatchback: all modols}''97 Dl6Y8 ongine (s€dan: KA' KC mod€lsl:
The scan tool indicates Diagnostic Trouble code (DTC) P0441: Evaporative Emission (EVAP) control system
insufficient purge flow.
Description
By monitoring the purge line vacuum with the MAP sensor, the ECM/PCM can detect insufficient EVAP control system
purge flow.
Possible Cau3e
. EVAP Purge Control Solenoid Valve
. EVAP Purge Control Solenoid Valve Circuit
. EVAP Control Canister
. Vacuum Lines
. ECM/PCM
Troubl93hooting Flowchart
Wire side of femaleterminals
EVAP PURGE CONTROI-sottNotD vALvE 2P
CoNNECTOR (Cl1al
r-+-r
I'l'l
lG-ro.*l'rr"r
O)
Y
(cont'd)
11-271
- The MIL has bsGn.eportad on.- DTC milal k rtored.
Pioblem vsrificJtion:1. Start the engine. Hold the
engine at 3,000 rPm with no
load {in Park or noutral) until
the radiator fan comes on.
2. Do the ECM/PCM Reset Proce'
dure,3. Connect the SCS service con-
nector.4. Test-drive under following con-
ditions on the road- Without any electrical load- A/T in E or E Position(M/T in 3rd-sth gear)- Engine sPeed betweon
1,200 - 2.400 rpm.- Decelerate {rom 50 mph (80
knl/h)to 15 mph (24 km/h)lntormittont lailuro, sFtorn b OK
at thi. timo. Ch€ck tor Poor con'
ncction3 or looac wir.3 at C144
{EVAP purgo control tolonoid
vrtv.l .nd ECir/FCttl.
ls DTC P0441 indicatod?
Ch.ck fo. !n op€n in the wiro l|(illinel:1. Turn the ignition switch OFF.
2. Disconnect the EVAP Purgecontrol solenoid valve 2P con_
neclor,3. Turn the ignition switch ON (ll)
4. Measur€ voltage between bodyground and the EVAP Purgecontrol solenoid valve 2P con-
nector terminal No 1.
Rop.ir opor in tho wir6 b€two€n
the EVAP purgo codtiol tolonoid
v.lvo rnd tho No 15 ALIERNA'
TOR SP SENSOR 17.5 A)lu.o.
{To page 11-272)

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Fuel Tank Pro3sure sensor 196 D16Y8 engine (coupe).'97 D15Y7 engine {coupe: KL model, sedan: KL (LX) modeu,'97
D16Y8 engine (coupe: all models, sedan: KL model, '98-all models) '99 - 00 D16Y5 engine with M/Tl:
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PTANK
{LT GRNI
vcc2(YEL/BLU}
Wire side oI female terminals
FUEL TANKPRESSURE SENSOR3P CONNECTOR (C7921
sG2IGRN/8LK)
Foc2l::il":"toolindicatesDiagnosticTroublecode(DTc)P0452:A|owvo|tageprob|emintheFue|TankPressure
The fuel tank pressure sensor converts fuel tank absolute pressure into electrical signals and inputs the EcM/PCM.
OUTPUTVOLTAGEtvt4.5
-? kPa(-50 mmHg,-2 in.Hg)
ECM/PCM CONNECTOR O I16P)
Wire side of female terminals
+7 kPs150 mmHg,2 in.Hg)
PRESSURE
(cont'd)
11-275
- The MIL has been reported on- DTC P0452 is stored.
Check the vacuum lines:
Check the vacuum lines of the
fuel tank pressure sensor for mis-
routing, leakage, breakage and
cloggrng.
Are the vacuum lines OK?
Problem v€ritication:1. Do the ECM/PCM Reset Proce
dure.2. Remove the luel fill caP.
3. Turn the ignition switch ON lll)4. Monitor the FTP Sensor volt_
age with the Honda PGM
Tester, or measure voltage
between bodY ground and
ECM/PCM terminal Dl5.lntermittent tailuro, sYstem i5 OK
dt this timo. Chock for Poot con-
neciion3 or loose wir* at C131
llocatod under right side ot dashl,
C4O1 (located .bove under'da3htuso/ielay box), C574 1C568)*
{located under acc€ss Panell.C792 lfuel tank pressule sen3or)
and EcM/PCM.
ls there approx. 2.5 V?
Check tol an op€n in wite (VCC2
line):1. Turn the ignition switch OFF
2. Reinstallthe fuel fill caP.3. Disconnect the fuel tank Pres'sure sensor 3P connector-4. Turn the ignition switch ON (ll)
5, Measure voltage between the
fuel tank pressure sensor 3P
connector No. l terminal and
No. 2 terminal.
Repair open in the wite betweenthe fuel tank Pr€s3ure a€n3or andth6 EcM/PcM (D1ol.ls there approx. 5 V?
(To page 11'276)

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'99 - 00 models excepi Dl6Y5 engine with M/T:
The scan tool indicates Diagnostic Trouble Code (DTC) P0452: A low voltage problem in the Fuel Tank Pressure
sensor.
The fuel tank pressure sensor converts fuel tank absolute pressure into electrical signals and inputs the ECM/PCM
OUTPUTVOLTAGE(vlt.5
0.5-7 kP.(-g) mmHg,-2 in.Hgl
+7 kP.
150 mmHg,2 in.Hgl
PRESSURE
I
Wire side of lemale terminals
FUEL TANKPRESSURE SENSORSUB.HARNESS6P CONNECTOR (C574 (C568)rl
vcc2(YEL/BLUIsG2{GRN/BLK}
Wire side o{ temale terminals
The MIL has been .eported on.
DTC P0452 is stored
Check the vacuum lines:
Check the vacuum lines of the
fuel tank pressure sensor lor mis-
routing, leakage, breakage and
cloggrng.
Are the vacuum hnes OK?
Problem veritication:1. Do the ECM/PCM Reset Proce-
du re,2. Bemove the fuel fill caP.
3. Turn the ignition switch ON {ll)
4. Monitorthe FTP Sensor voltage
with the Honda PGM Tester' or
measure voltage between body
groLrnd and ECM/PCM connec_
tor terminalA29.
lntermitlent tailure, 3Ystem b OK
at this time. Check for Poor con'
nections or loose wire3 at C131
{located under right side of dash},
C401 {located above under'dash
tuse/relay box), C574 (C568)*
llocdted under access Panel),C792 (tuel rank Prcssure sensorl
and ECM/PCM.
ls there approx.2 5 V?
Check for an open in wire {VCC2
line):1. Turn the ignition switch OFF.
2. Reinstall the ltrel fill caP
3, Remove the access Panel from
the floor.4. Disconnect the fuel tank Pres'sure sensor sub-harness 6P
5. Turn the ignition switch ON (ll).
6. At the access Panel side, mea_
sure voltage between the fuel
tank Pressure sensor sub-nar-
ness 6P connector No 5termi
nal and No. 6 termlnal.
Repair open in tho wire between
th6 fu€l tank Prossuro sen3oa and
the ECM/PCM lc28).ls there approx 5 V?
ECM/PCM CONNECTOR A (32P)
PTANK {LT BLUI
I
ll
(To page '11-278)
(cont'd)