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DTC P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1); DTC P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1): Description

WARNING: This page is about a different car, the 2007 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

Refer to DTC P2195 .

HINT:

Although each DTC title says "oxygen sensor," these DTCs are related to the air-fuel ratio sensor (A/F sensor).
The ECM provides a pulse width modulated control circuit to adjust current through the heater. The A/F sensor heater circuit uses a relay on the +B side of the circuit.

Fig 1: Oxygen (A/F) Sensor - Circuit Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DTC DETECTION CONDITION

DTC No.	DTC Detection Condition	Trouble Area
P0031	Heater current is less than 0.8 A when the heater operates (1 trip detection logic)	Open or short in heater circuit of A/F sensor A/F sensor heater EFI M relay (integration relay) ECM
P0032	Heater current exceeds 10 A when the heater operates (1 trip detection logic)	Short in heater circuit of A/F sensor A/F sensor heater EFI M relay (integration relay) ECM

HINT:

Sensor 1 refers to the sensor mounted before the TWC and is located near the engine assembly.
Sensor 2 refers to the sensor mounted after the TWC and is located far from the engine assembly.