2000 HONDA CIVIC o ring

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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

4
The scan tool indicates Dlagnostic Trouble cod€ {DTc} Po4ol: lnsufficient flow in the Exhaust Gas Recirculation
(EGR) svstem.
Doscription
Deterioration (clogging, leakage, etc.) in the EGR line or EGR valve is detected by means of the changes in MAP before
and after the operation of the EGR valve.
lf deterioration has been detected during two cons€cutive driving cycles, the MIL will come on and DTC P0401 will be
stored.
Po$ible Causeg
. Clogging. leakage in the EGR line
. Faulty EGR valve
Troubleshooting Flowchart
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- Tho MIL ht! bacn rgportod on.- DTC m40l is 3torod.
Problom vorification:
1. Do the ECM/PCM Reset Proce-
dure.2. Connect the SCS service con-
nector,3. Tost-drive under the following
conditions.- Without any electrical load- Decelerate lrom 55 mPh(88 km/h)lor at least 5 sec-
onos
lntormiftam f!ilu.a, ayltam ia OK
.t thb time,
- Clo.n tho inttkc mlnifold EGRport wittr carbursto. clotner.- Cl.an the pa$lgo insido tho
EGR valvo with crrburator
cloanol or aoglaca tha vllvo.

Emission Control System
Positive Crankcase Ventilation IPCVI System
Descripiion
The Positive Crankcase Ventilation (PCV) system is
designed to prevent blow-by gas from escaping to the
atmosphere. The PCV valve contains a spring-loaded
plunger. When the engine starts, the plunger in the PCV
valve is lifted in proportion to intake manifold vacuum
and the blow-by gas is drawn directly into the intake
manifold.
D15Y5, D16Y8, 816A2 ongins:
BREATHERHOSE
Dl6'|11 6ngin6:
-: aLOW-BY VAPOR-: FnESH AIF
11-266
tJ
lrcpection
1. Check the PCV hoses and connections for leaks and
clogging.
2. At idle, make sure there is a clicking sound from the
PCV valve when the hose between the PCV valve
and the intake manifold is lightly pinched with your
fingers or pliers,
D16Y5, D16Y8 ongins:
BREATHERHOSE
PCV VALVE
Gently pinch here.
Bl6A2 engins:VALVE
lf there is no clicking sound, check the PCV valve
grommet for cracks and damage. If the grommet is
OK, replace the PCV valve and recheck.
PCV

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Evaporative Emission (EVAPI Controls
Description
The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The
system consists of the foliowing components:
A. Evaporative Emission (EVAP) Control Canisto]
An EVAP control canister is used for the temporary storage of fuel vapor until the fuel vapor can be purged from the
EVAP control canister into the engine and burned.
B. Vapor Purge Control System
EVAP control canister purging is accomplished by drawing fresh air through the EVAP control canister and into a port
on the intake manifold. The purging vacuum is controlled by the EVAP purge control solenoid valve.
I'96 D16Y5 engine,'96 Dl6Y7 engine,'96 D16Y8
engine (sedan),'97 D16Y5 engine,'97 D16Y7
engine (couper KA, KC models, sedan: KA, Kc'
KL iDX) models, hatchback: all models), '97
D 16Y8 engine (sedan: KA, KC models)l
I'96 D16Y8 engine (coupe),'97 D16Y7 engine
(coupe: KL model, sedan: KL (LX) model)"97
D16Y8 engine (coupe: all models, sedan: KL model)'98-all models,'99-all models,'00-all modelsl
I
c.
D.
or
l'lc COMPRESSOR CLUTCH ON
and
INTAKE AIR TEMPERATURE ABOVE 160"F (41'C)
Fuel Tank Vapor Control System
When fuel vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and
regulates the flow of fuel vapor to the EVAP control canister.
Onboard Refueling Vapor Recovery (ORVRI System {'99 - 00 models}
During refueling. the oRVR {onboard Refueling Vapor Recovery) vent shut valve opens with the pressure in the fuel
tank. and feeds the fuel vapor to the EVAP control canister.
t(cont'd)
11-267
EVAP PURGE CONTROL SOLENOID VALVE DUTY CON-
TROLLED AFTER STARTING ENGINE
ENGINE COOLANT TEMPERATURE ABOVE 154'F {68"C)
INTAKE AIR TEMPERATURE ABOVE 32'F (O'C)
and
VEHICLE SPEED ABOVE O MILE (O KM/h}
ENGINE COOLANT TEMPERATURE ABOVE 154'F (68'C)

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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)

Emission Control System
(From page 11 285)
Check lor an op€n in the wire{PCS line}:1. Turn the ignition switch OFF.2, Reconnect the 2P connector lothe EVAP purge control sole-noid valve.3. Turn the ignition switch ON (lll.4. Measure vo ltage betweenECM/PCM connector terminals415 and A]0.
Repai. op€n in the wire bGtweenthe EVAP purge control solenoidvalve and the ECM/PCM {A151.
Substitute a known-good ECM/PCM and retest. tf sympiom/indi-cation goes away, replac6 theoriginal ECM/PCM.
Evaporative Emission (EVAPI Controls (cont'd)
(From page 11'285)
(To page 'l1 287)
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ECM/PCM CONNECTOR A {32P}
PCS{RED/YEL)
PGl
{BLK)
Wire side oftemaleterminals
EVAP BYPASSSOLENOID VALVE
O.RINGBeplace.
PUMP/GAUGE,0 - 30 in.HgA973X -
041 -
xxxxx
EVAP TWO WAY VALVE
EVAP IWO WAY
Check the EVAP two way valvo:See EVAP two way valve test (seepage 11'294).
Replace tho EVAP two way valve.
Check the EVAP bypr$ 3olenoid
1. Disconnect the vacuum hosefrom the EVAP two way valveand connect a vacuum pumpto the hose.2. Turn the ignition switch ON lll).3. Apply vacuum to the hose.Check tor a short in the wire{2WBS linel:Disconnect the 2P connector fromthe EVAP bypass solenoid valve.Does the valve hold vacuum?
Repair short in the wire betwe€nEVAP bypass sol€noid valve andrhe ECM/PCM lA28).
Does the valve hold vacuum?
11-286

Emission Control System
Evaporative Emission {EVAP) Controls (cont'dl
\J
tF1456-l
tP14sz-l
EVAPCONTROLCANISTERVENTSHUTVALVE
O.RINGReplace.
EVAPCONTROLCANISTER
ECM/PCM CONNECTOR A I32PI
(To page 11'289)
'99 - 00 modols except Dl6Y5 engine with M/T:
The scan tool indicates Diagnostic Trouble Code (DTC) P1456: Evaporative Emission (EVAP) control system leak
detected (fuel tank svstem).
The scan tool indicates Diagnostic Trouble Code (DTC) P1457: Evaporative Emission (EVAP) control system leak
detected (EVAP control canister system).
Possible Cause
. Fuel fill cap
. Vacuum Connections
. FuelTank
. EVAP Control Canister Vent Shut Valve
. EVAP Control Canister Vent Shut Valve Circuit
. EVAP Purge Control Solenoid Valve
o EVAP Purge Control Solenoid Valve Circuit
. EVAP Bypass Solenoid Valve
0 -30 in,Hg
. EVAP Bypass Solenoid Valve Circuit
. Fuel Tank Pressure Sensor
. Fuel Tank Pressure Sensor Circuir
. EVAP Control Canister
. ORVR vent shut valve
. ORVR vapor recirculation valve
. Throttle Body
Troubleshooting Flowchart
VACUUMPUMP/GAUGE,A973X - oal -
xxxxx
T-t
t\
The MIL has been reported on.DTC P1456 o. P1457 is stored.
Check the EVAP cont.ol canistervent shul valve:1. Disconnect the vacuum hosefrom the EVAP three wayvalve and connect a vacuumpump to the hose.2. Remove the EVAP controlcanister vent shut valve fromtne canrster.3. Turn the ignition switch ON (ll).
4. Apply vacuum to the hose.Check for a short in the wiro(VSV linel:Disconnect the 2P connector fromthe EVAP control canister ventDoes the vaive hold vacuum?
RoDair 3hort in the wire botwe€nthe EVAP control canilter ventshut valve and the ECM/PCM{A4t.
Does the valve hold vacuum?Check the EVAP cont.ol canisterv€nl shut valve:1. Turn the ignition switch OFF.2. Connect ECM/PCM connectorterminal A4 to body groundwith a jumper wire.3. Turn the ignition switch ON (ll).
4. Apply vacuum to the hose.
Reolace the EVAP control canis-ter veni shut valve.
Does the valve hold vacuum?
Wire side of female terminals
11-288
lTo page 11-289)

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7. Connect a second vacuum pump to the OBVR signal
nose.
VACUUM PUMP/GAUGE.0 - 30 in.HgA973X - 041 -
xxxxx
Apply vacuum (1 pump) to the ORVR signal hose,
then check the vacuum on the pump in step 6.
. lf the vacuum holds, replace the ORVR vent shut
valve.
. lf the vacuum is released, the ORVR vent shut
valve is OK.
Disconnect the ORVR quick disconnect from the EVAP
canister, then plug the port on the canister.
Reapply vacuum (80 pumps).
. lf the vacuum holds, reDlace the ORVR vent shut
valve,
. lf the vacuum does not hold, inspect the EVAP can-
ister vent shut valve O-ring. lf the O-ring is OK,
replace the EVAP canister and repeat step 4.
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11-297
ORVR Vent Shut Valve Replacement
1. Remove the fuel tank (see page 1 1-242).
2. Remove the ORVR vent shut valve from the fuel tank.
3. lnstall oarts in the reverse order of removal.