Suzuki Baleno Manual page 1292

6-1-62 ENGINE GENERAL INFORMATION AND DIAGNOSIS (G13/G16 ENGINE WITH WU TWC)
DTC P0136 HEATED OXYGEN SENSOR (HO2S) CIRCUIT MALFUNCTION
(SENSOR-2)
CIRCUIT DESCRIPTION
Main
fuse
DTC DETECTING CONDITION
DTC will set when A or B condition is detected.
A. Max. output voltage of HO2S-2 is lower than specified value or
Min. output voltage is higher than specified value while vehicle
driving.
B. Engine is warmed up and HO2S-2 voltage is 4.5 V or more.
(circuit open)
: 2 driving cycle detection logic, monitoring once / 1 driving.
Ignition
switch
To HO2S-1
heater
To other sensor
Heater
POSSIBLE CAUSE
D Exhaust gas leakage
D "Bl" or "P" circuit open or short
D Heated oxygen sensor-2 malfunction
D Fuel system malfunction
ECM
(PCM)