Suzuki Wagon R Manual page 1147

DTC P0135 HEATED OXYGEN SENSOR (HO2S) HEATER CIRCUIT
MALFUNCTION (SENSOR-1)
CIRCUIT DESCRIPTION
Main
fuse
"IG COIL"
DTC DETECTING CONDITION
DTC will set when A or B condition is met.
A:
D Low voltage at terminal E23-8 when engine is
running at high load.
B:
D High voltage at terminal E23-8 when engine is
running under condition other than above.
: 2 driving cycle detection logic, Continuous
monitoring.
DTC CONFIRMATION PROCEDURE
WARNING:
D When performing a road test, select a place where there is no traffic or possibility of a traffic accident
and be very careful during testing to avoid occurrence of an accident.
D Road test should be carried out with 2 persons, a driver and a tester.
1) Turn ignition switch OFF.
2) Clear DTC with ignition switch ON, start engine and keep it at idle for 1 min.
3) Start vehicle and depress accelerator pedal fully for 5 sec. or longer.
4) Stop vehicle.
5) Check DTC in "DTC" mode and pending DTC in "ON BOARD TEST" or "PENDING DTC" mode.
Ignition
switch
To HO2S-2 heater
GENERAL INFORMATION AND ENGINE DIAGNOSIS 6-1-55
To other sensors
BRN / WHT
Heater
POSSIBLE CAUSE
D HO2S-1 heater circuit open or shorted to ground
D ECM (PCM) malfunction