Dtc P0155 Ho2S (Bank-2 Sensor-1) Heater Circuit Malfunction - Suzuki 2000 Grand Vitara SQ625 Service Manual

6-1-78 ENGINE (H25 ENGINE)

DTC P0155 HO2S (BANK-2 SENSOR-1) HEATER CIRCUIT MALFUNCTION

WIRING DIAGRAM
Refer to DTC P0150.
DTC DETECTING CONDITION AND TROUBLE AREA
DTC DETECTING CONDITION
Current of HO2S heater is higher than specified value or
lower than specified value.
DTC CONFIRMATION PROCEDURE
NOTE:
Check to make sure that following conditions are satisfied when using this DTC CONFIRMATION PROCE-
DURE.
WARNING:
D When performing a road test, select a place where there is no traffic or possibility of a traffic accident
and very careful during to avoid occurrence of an accident.
D Road test, should be carried out with 2 person, a driver and tester, on a level road.
D Intake air temperature: between –14_C and 70_C (6.8_F and 158_F)
D 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
STEP
1 Was "ENGINE DIAG. FLOW TABLE" performed?
2 HO2S Heater check:
(1) With ignition switch OFF, disconnect HO2S heater
relay.
(2) Check resistance between C51-3-5 and E139-2.
Is the resistance 3 – 3.6 W at 20_C?
3 HO2S Heater Power Supply check:
(1) With ignition switch ON leaving engine OFF, check
voltage between E139-3 and ground, E139-1 and
ground.
Is each voltage 10 – 14 V?
4 HO2S Heater Control Circuit check:
(1) With ignition switch OFF, install HO2S heater relay.
(2) With ignition switch ON leaving engine OFF, check
voltage between C51-3-5 and ground.
Is the voltage 10 – 14 V?
ACTION
TROUBLE AREA
HO2S
HO2S circuit
ECM (PCM)
YES
GO to Step 2.
Go to Step 3.
Go to Step 4.
Substitute a known-
good ECM (PCM)
and recheck.
NO
Go to "ENGINE
DIAG. FLOW
TABLE".
Faulty "Bl", "B/R" wire.
Faulty HO2S.
18 and/or 21 fuse
blown.
If OK, faulty "B/W"
wire or "Bl/W" wire.
Faulty HO2S heater
relay or "B/R" wire
shorted to ground
circuit.
If OK, substitute a
known-good ECM
(PCM) and recheck.