Thermostat
The HDS or the scan tool indicates Diagnostic Trouble Code (DTC) P1486: Range/Performance Problem in
Thermostat.
NOTE: If the DTCs listed below are stored at the same time as DTC P1486, troubleshoot those DTCs first, then recheck for
P1486.
P0107, P0108, P1128, P1129: MAP Sensor
P2227, P2228, P2229: Barometric Pressure Circuit
P1259, P1279: VTEC system
P0401: EGR Flow Insufficient
P0404: EGR Valve Lift Insufficient
P0406: EGR Valve Position Sensor High Voltage
P0125, P0116, P0117, P0118: Engine Coolant Temperature Circuit
P0112, P0113: Intake Air Temperature Circuit
P0345, P0349, P1336, P1337: CKP Sensor 1/2
P0300: Random Misfire
P0301, P0302, P0303, P0304, P0305, P0306: Cylinder 1, 2, 3, 4, 5 or 6 Misfire detected.
P0506, P0507: Idle Control System Malfunction
P0511: Idle Air Control Valve
DTC P1486 can set occasionally when the hood is opened.
Troubleshooting
— The MIL has been reported on.
— DTC P1486 is stored.
1. Turn the ignition Switch OFF.
2. Check the engine coolant
level.
Is the engine coolant level low?
Does the radiator fan keep
running?
YES
Check the radiator fan circuit,
radiator fan switch circuit and
the radiator fan switch.
It they are OK, substitute the
PCM and recheck.
If the symptom/indication goes
away, replace the original PCM.
Refill the engine coolant. If neces-
sary, check the cooling system.
Test the thermostat.
Check for the radiator for circuit:
1. Turn the ignition switch ON
(II).
2. Check the radiator fan.ProCarManuals.com
PGM-FI Syste m
NOTE: I f th e DTC s liste d belo w ar e store d a t th e sam e tim e a s DT C P1486 , troubleshoo t thos e DTC s first , the n rechec k fo r
P1486 .
P0107 , P0108 , P1128 , P1129 : MA P Senso r
P1106 , P1107 , P1108 : Barometri c Pressur e Circui t
P1259 , P1279 : VTE C syste m
P0401 : EG R Flo w Insufficien t
P1491 : EG R Valv e Lif t Insufficien t
P1498 : EG R Valv e Positio n Senso r Hig h Voltag e
P0116 , P0117 , P0118 : Engin e Coolan t Temperatur e Circui t
P0112, P0113 : Intak e Ai r Temperatur e Circui t
P0335 , P0336 , P1336 , P1337 : Crankshaf t Positio n Senso r 1/ 2
P0300 : Rando m Misfir e
P0301 , P0302 , P0303 , P0304 , P0305 , P0306 : Cylinde r 1 , 2 , 3 , 4 , 5 or 6 Misfir e detected .
P0505 : Idl e Contro l Syste m Malfunctio n
P1508 : Idl e Ai r Contro l Valv e
DT C P148 6 ca n se t occasionall y whe n th e hoo d i s opened .
— Th e MI L ha s bee n reporte d on .
— DT C P148 6 is stored .
1. Tur n th e ignitio n Switc h OFF .2. Chec k th e engin e coolan t
level .
I s th e engin e coolan t leve l low ?
Doe s th e radiato r fa n kee p
running ?
YES
Chec k th e radiato r fa n circuit ,
radiato r fa n switc h circui t an d
th e radiato r fa n switch .
I t the y ar e OK , substitut e th e
PC M an d rechec k (se e pag e 11-42
fo r immobilize r information) .
I f th e symptom/indicatio n goe s
away , replac e th e origina l PCM . Refil
l th e engin e coolant . I f neces -
sary , chec k th e coolin g system .
Tes t th e thermostat .
NO
N
O
YE S
Chec k fo r th e radiato r fo r circuit :
1 . Tur n th e ignitio n switc h O N
(II).2. Chec k th e radiato r fan .
Troubleshootin g
('00 - 0 1 model ) Th e sca n too l indicate s Diagnosti c Troubl e Cod e (DTC ) P1486 : Range/Performanc e Proble m in
Thermostat .
Thermostat
ProCarManuals.com
