DTC P0031, P0032, P101D; Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) [08/2014 - ]: Description

Refer to DTC P2195.

HINT:

When any of these DTCs is stored, the ECM enters fail-safe mode. The ECM turns off the air fuel ratio sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.
Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
Sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.
The ECM has a pulse width modulated control circuit to adjust the current through the heater. The air fuel ratio sensor heater circuit uses a relay on the +B side of the circuit.

Fig 1: Reference Bank 1 Sensor 1 Circuit Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory	Note
P0031	Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)	Air fuel ratio sensor heater current is less than 0.8 A, even when the airfuel ratio sensor heater duty cycle is 30% or higher (1 trip detection logic).	Open in air fuel ratio sensor (sensor 1) heater circuit Air fuel ratio sensor (sensor 1) EFI-MAIN NO. 2 relay ECM	Comes on	DTC stored	DTC for Mexico Models - Applies
P0032	Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)	Air fuel ratio sensor heater current reaches the high limit (1 trip detection logic).	Short in air fuel ratio sensor (sensor 1) heater circuit Air fuel ratio sensor (sensor 1) EFI-MAIN NO. 2 relay ECM	Comes on	DTC stored	DTC for Mexico Models - Applies
P101D	A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON	The heater current is higher than the specified value while the heater is not operating (1 trip detection logic).	Short in air fuel ratio sensor (sensor 1) heater circuit ECM	Comes on	DTC stored	DTC for Mexico Models - Applies

HINT: