DTC P2195, P2196; Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1) [12/2012 - 08/2014]: Description

HINT:

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 air fuel ratio sensor generates a voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection duration. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is a planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are a narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, and therefore sensor activation is accelerated.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.

*: Value changes inside the ECM. Since the air fuel ratio sensor is a current output element, the current is converted into a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

Fig 1: Identifying Air Fuel Ratio Sensor & Air Fuel Ratio Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory	Note
P2195	Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)	Either of the following conditions (A) or (B) met: (A) Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic): Air fuel ratio sensor voltage is higher than 3.8 V. Heated oxygen sensor voltage is 0.21 V or higher. (B) While the fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio sensor current is 2.2 mA or higher for 3 seconds (2 trip detection logic).	Open or short in air fuel ratio sensor (sensor 1) circuit Air fuel ratio sensor (sensor 1) Intake system Fuel pressure Fuel injector assembly ECM	Comes on	DTC stored	DTC for Mexico Models - Not apply
P2196	Oxygen (A/F) Sensor Signal Stuck Rich (Bank 1 Sensor 1)	Either of the following conditions (A) or (B) is met: (A) Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic): Air fuel ratio sensor voltage is less than 2.8 V. Heated oxygen sensor voltage is less than 0.69 V. (B) While the fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio sensor current is less than 0.7 mA for 3 seconds (2 trip detection logic).	Open or short in air fuel ratio sensor (sensor 1) circuit Air fuel ratio sensor (sensor 1) Intake system Fuel pressure Fuel injector assembly ECM	Comes on	DTC stored	DTC for Mexico Models - Not apply

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P2195

Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)

Either of the following conditions (A) or (B) met:
(A)

Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic):
1. Air fuel ratio sensor voltage is higher than 3.8 V.
2. Heated oxygen sensor voltage is 0.21 V or higher.

(B)

While the fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio sensor current is 2.2 mA or higher for 3 seconds (2 trip detection logic).

Open or short in air fuel ratio sensor (sensor 1) circuit
Air fuel ratio sensor (sensor 1)
Intake system
Fuel pressure
Fuel injector assembly
ECM

Comes on

DTC stored

DTC for Mexico Models
- Not apply

P2196

Oxygen (A/F) Sensor Signal Stuck Rich (Bank 1 Sensor 1)

Either of the following conditions (A) or (B) is met:
(A)

Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic):
1. Air fuel ratio sensor voltage is less than 2.8 V.
2. Heated oxygen sensor voltage is less than 0.69 V.

(B)

While the fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio sensor current is less than 0.7 mA for 3 seconds (2 trip detection logic).

Open or short in air fuel ratio sensor (sensor 1) circuit
Air fuel ratio sensor (sensor 1)
Intake system
Fuel pressure
Fuel injector assembly
ECM

Comes on

DTC stored

DTC for Mexico Models
- Not apply

HINT:

When any of these DTCs is stored, check the air fuel ratio sensor voltage output by entering the following menus on the Techstream: Powertrain / Engine and ECT / Data List / Gas AF Control / AFS Voltage B1S1.
Short-term fuel trim values can also be read using the Techstream.
The ECM regulates the voltages at the A1A+ and A1A- terminals of the ECM to a constant level. Therefore, the air fuel ratio sensor voltage output cannot be confirmed without using the Techstream.
If an air fuel ratio sensor malfunction is detected, the ECM stores a DTC.