Toyota Celica 2005 Repair Manual page 560

MONITOR DESCRIPTION
The sending portion of the heated oxygen sensor has a zirconia element which is used to detect oxygen
concentration in the exhaust. If the zirconia element is at the proper temperature and difference of the oxy-
gen concentration between the inside and outside surface of sensor is large, the zirconia element will gener-
ate voltage signals. In order to increase the oxygen concentration detecting capacity in the zirconia element,
the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor. When
current in the sensor is out of the standard operating range, the ECM interprets this as a fault in the heated
oxygen sensor and sets a DTC.
Example:
The ECM will set a high current DTC if the current in the sensor is more than 2 A when the heater is OFF.
Similarly, the ECM will set a low current DTC if the current is less than 0.25 A when the heater is ON.
MONITOR STRATEGY
Related DTCs
Required sensors/components
Frequency of operation
Duration
MIL operation
Sequence of operation
2005 CELICA (RM1131U)
DIAGNOSTICS −
P0031
P0032
P0037
P0038
Main sensors/components
Related sensors/components
Continuous
0.2 sec.
1 driving cycle
None
559
ENGINE (2ZZ−GE)
Heated oxygen sensor heater current bank 1
sensor 1 (Low current)
Heated oxygen sensor heater current bank 1
sensor 1 (High current)
Heated oxygen sensor heater current bank 1
sensor 2 (Low current)
Heated oxygen sensor heater current bank 1
sensor 2 (High current)
Heated oxygen sensor
Vehicle speed sensor
DI−361