ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE) 6-1-89
DTC P0155 HO2S (Bank-2 Sensor-1) Heater Circuit Malfunction
WIRING DIAGRAM
Refer to DTC P0150.
DTC DETECTING CONDITION AND TROUBLE AREA
DTC CONFIRMATION PROCEDURE
• Intake air temperature : between –14°C and 70°C (6.8°F and 158°F)
• Atmospheric pressure : higher than 560 mmHg (Altitude : lower than 2790 m (9150 ft))
1) With ignition switch OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC by using scan tool if any.
3) Start engine and warm up to normal operating temperature.
4) Increase vehicle speed to 56 km/h (35 mph) or more.
5) Keep above vehicle speed for 5 min. (Throttle valve operating is kept constant in this step.)
6) Stop vehicle and run engine at idle speed for 1 min.
7) Check DTC and pending DTC by using scan tool.
DTC TROUBLESHOOTING
DTC DETECTING CONDITION TROUBLE AREA
Current of HO2S heater is higher than specified value or
lower than specified value.
HO2S
HO2S circuit
ECM (PCM)
NOTE:
Check to make sure that following conditions are satisfied when using this DTC CONFIRMATION PRO-
CEDURE.
WARNING:
• When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and very careful during to avoid occurrence of an accident.
• Road test, should be carried out with 2 person, a driver and tester, on a level road.
Step Action Yes No
1Was “Engine Diag. Flow Table” performed? Go to Step 2. Go to “Engine Diag. Flow
Ta bl e ”.
2 HO2S Heater check :
1) With ignition switch OFF, disconnect HO2S
heater relay (1).
2) Check resistance between C51-3-5 and
“BLU” wire terminal of HO2S heater relay
coupler (2).
Is the resistance 3 – 3.6
Ω
at 20°C?
Go to Step 3. Faulty “BLU”, “BLK/RED”
wire.
Faulty HO2S.
3 HO2S Heater Power Supply check :
1) With ignition switch ON leaving engine OFF,
check voltage between “BLK/WHT” wire ter-
minal of HO2S heater relay coupler (2) and
ground, “BLU/WHT” wire terminal of HO2S
heater relay coupler (2) and ground.
Is each voltage 10 – 14 V?
Go to Step 4. Main fuse and/or “IG
COIL” fuse blown.
If OK, faulty “BLK/WHT”
wire or “BLU/WHT” wire.
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