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PGM-FI System
'99 - 00 models:
- The MIL has bsen reported on.- DTC P0131 ir storod.
Problem ve fication:1. Do the ECM/PCM Reset Pro-cedure,2. Start the engine. Hold theengine at 3,000 rpm with noload {in Park or neutral) untillhe radiator tan comes on.3. Check the Primary HO2S(Sensor 1) oltput voltage withthe scan tool during accelera-tion using wide op€n throttle.
Inl.rmittant failura, 3yrtam i! OKat thb tim.. Ch.ck tor poor con-nectiona oa looaa wlraa al C111{Pri|n.ry HO2S, Son3or 1l .nd .ttho ECM/FCM,
Does the voltage stay at 0.5 Vor less?
Check tho fuel pressure (see pago1r,178).
R.p.ir th. fu€l lupply ry!t.m.
Chock lor a short in tho HO2S:1. Turn the ignition switch OFF.2. Disconnect the Primary HO2S(Sensor 1) 4P connector.3. St6rt the engine and lot it idle.4. Check the Primary HO2S(Sensor 1) output voltage withthe scan tool,
Does it stay 6t 0.5 V or less?Rephc. th6 HO2S (S.n3or 11.
Chock for a short in tho wirc(PHO2S lino):1. Turn the ignition switch OFF.2. Disconnect the ECM/PCM con-nector C (31P).
3. Check tor continlity betweenthe Primary HO2S {Sensor 'l}
4P connector terminal No. Iand body ground.
Ragah rhort in tha wira balwoanth. ECM/PCM {Cl61 rnd thcPrirn.ry HO2S (S.n3or 11.
Substltut6 a known-good ECM/PCM and recheck. lf rymptom/indicrtion 00os away, raplaco thcoriginal ECM/PCM.
Primary Heated Oxygen Sensor (Primary HO2SI (Sensor 1l (cont'd)
PRIMARY HO2S (Son.or 1l aP CONNECTOR |C111)
PHO2S T--1rwHTr f-T---]
--1 1 2lI t--- 1t6)lslrlv L__r__J
_L
Wire side ol female terminals
11-112
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Secondary Heated Oxygen Sensor (Secondary HO2S) (Sensor 2)
The scan tool indicates Diagnostic Trouble code (DTC) P0137: A low voltage problem in the secondary Heated
Oxygen Sensor (Secondary HO2S) (Sensor 2) circuit.
SECONDARY HO2S ls.nlor 2)4P CONNECTOB lC721l
Wire side of lemale terminals
(cont'd)
11-117
The MIL hrs been reported on.DTC P0137 is stored.
Problem veritication:1. Do the ECM/PCM Reset Pro'cedure.2. Start the engine. Hold theengine at 3,000 rpm wilh no
load (in Park or neutral) untalthe radiator {an comes on,3. Check the Secondary H02S
lSensor 2) output voltage at3,000 rpm with the scan tool.
lnlermittent failure, 3ystem i5 OK
at this time. Check tor Poor con'
noction3 or loose wires at C127
{locatod on ECM/PCM bracket},C721 (Secondary HO2S, Sensor2l and at the ECM/PCM.
Does the voltage stay at 0.3 V
or less?
Check for a short in the SecondaryHO2S:1. Turn the ignition switch OFF.2. Disconnect the SecondaryHO2S lSensor 2) 4P connector.3. Start the engine.4. Check the Secondary HO25(Sensor 2) output with the scantool.
Check lor a short in the wire(SHO2S linel:1. Turn the ignition switch OFF.2. Disco n nect the ECM/PCMconnector {D (16P}, A (32P}').
3. Check for continuity betweenthe Secondary HO2S (Sensor
2i 4P connector terminal No. 1and body ground.
Reoair short in the wire b€twoen
rhe ECM/PCM |D14, 423*l and
the Secondary HO2S {Sensor 2).
Substitute a known-good ECM/PCM and rocheck. lf symptom/indication goes away, replacethe original ECM/PCM.
*: '98 - 00 modeis
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Page 323 of 1395

Heated Oxygen Sensor (HO2S| Heater
The scan tool indicatos Diagnostic Trouble Code (DTC) P0135: A problem in the Primary Heated Oxygen Sensor
{Primarv HO2S) (Sensor 1) Heater circuit.
The scan tool indicates Diagnostic Trouble Code (DTC) P0141: A problem in the Secondary Heated Oxygen Sensor
(Secondary HO2S) (Sensor 2) Heater circuit.
Fol3sl
Fo11tl
PBIMARY HO2S ls.n.or ll 4PCONNECTOR (CI 1 1 I, SECONDARYHO2S ls.n.o.2l aP CONNECTORlc721l.
Terminal side of male t€rminals
PRIMARY HO2S lson.o. 1l aPCONNECTOR {Cl 1 1 }, SECONDARYHO2S ls.nror 21 4P CONNECTORtcr21l.
so2sHTctBLK/WHn.
PO2SHTC(BLK/
WHTItGlIBLKAAIHTI'
Wire sid€ of lemale terminals
('97 model: To page '11-122)
('98 - 00 models: To page 11-'123)
*: P0141
('97 model: To page'11-122)
1'98 - 00 modelsl To page 11-123)(cont'd)
11-121
- Th6 MIL h.. bocn roponod on.- DTC P0135, and/oi mlal arestored.
Probl.m verification:1. Do the ECM/PCM Resot Pro-cedure,2. Start the engine.Int.rrnittaii frilurc, awtom ir OKat thi3 time. Chock lor poor con-n.ctiona or loosa wiro3 !t C111
lPrim.ry HO2S, Sen3o. 11. C12?llocatcd on ECM/PCM br.ck.t),C721 lsocond.ry Ho2s, s.n3or2r and at tho ECM/PCM.
Ch.ck ior an opon or shoYt in theHO2S:1. Turn the ignition switch OFF.2. Disconnoct the Ho2s (Primary
or Secondary*) (Sensor 1 orSensor 2)4P conneclor.3. At the HO2S side, measureresistance between the HO2S4P connector terminals No. 3and No.4.
ls there 10 - 40 0?
Check for continuity betweenbody ground and the HO2S 4Pconnector terminals No. 3 andNo. 4 individually.
Check tor an op6n or 3hort in thewires IPO2SHTC, SO2SHTC'linel:1. Turn the ignition swhch ON {ll).2. Moasure voltage between theHO2S 4P connector terminalsNo.3 and No.4.
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Page 324 of 1395