SFI SYSTEM, Diagnostic DTC:P2195, P2196

DTC Code	DTC Name
P2195	Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)
P2196	Oxygen (A/F) Sensor Signal Stuck Rich (Bank 1 Sensor 1)

DESCRIPTION

Tech Tips

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 time. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is the 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 the narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the 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.

DTC No.	DTC Detection Condition	Trouble Area
P2195	Conditions (a) and (b) continue for 10 seconds or more (2 trip detection logic) (a) Air fuel ratio sensor voltage is more than 3.8 V (b) Heated oxygen sensor voltage is 0.21 V or more	Open or short in air fuel ratio sensor (sensor 1) circuit Air fuel ratio sensor (sensor 1) Air fuel ratio sensor (sensor 1) heater Air fuel ratio sensor heater circuit Intake system Fuel pressure Fuel injector ECM
P2195	While fuel-cut operation performed (during vehicle deceleration), air fuel ratio sensor current 3.6 mA or more for 3 seconds (2 trip detection logic)	Air fuel ratio sensor ECM
P2196	Conditions (a) and (b) continue for 10 seconds or more (2 trip detection logic) (a) Air fuel ratio sensor voltage is less than 2.8 V (b) Heated oxygen sensor voltage is below 0.69 V	Open or short in air fuel ratio sensor (sensor 1) circuit Air fuel ratio sensor (sensor 1) Air fuel ratio sensor (sensor 1) heater Air fuel ratio sensor heater circuit Intake system Fuel pressure Fuel injector ECM
P2196	While fuel-cut operation is performed (during vehicle deceleration), air fuel ratio sensor current is less than 1.0 mA for 3 seconds (2 trip detection logic)	Air fuel ratio sensor ECM

Tech Tips

When any of these DTCs are set, check the air fuel ratio sensor voltage output by selecting the following menu items on the intelligent tester: Powertrain / Engine and ECT / Data List / AFS Voltage B1S1.
Short-term fuel trim values can also be read using the intelligent tester.
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 intelligent tester.
If a air fuel ratio sensor malfunction is detected, the ECM sets a DTC.

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

CAUTION:

Strictly observe posted speed limits, traffic laws, and road conditions when performing these drive patterns.

Tech Tips

This confirmation driving pattern is used in the "PERFORM CONFIRMATION DRIVING PATTERN" procedure of the following diagnostic troubleshooting procedure.

(a) Connect the intelligent tester to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the tester on.
(d) Clear the DTCs Click here.
(e) Start the engine, and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher (Step "A").
(f) Enter the following menus to check the fuel-cut status: Powertrain / Engine and ECT / Data List / Idle Fuel Cut.
(g) Drive the vehicle at between 60 km/h and 120 km/h (38 mph and 75 mph) for at least 10 minutes (Step "B").
(h) Change the transmission to 2nd gear (for A/T models) or M position, 2nd gear (for CVT models) (Step "C").
(i) Drive the vehicle at the proper vehicle speed to perform fuel-cut operation (refer to the following HINT) (Step "D").
Tech Tips

Fuel-cut is performed when the following conditions are met:
- Accelerator pedal is fully released.
- Engine speed is 2500 rpm or more (fuel injection returns at 1400 rpm).
(j) Accelerate the vehicle to 64 km/h (40 mph) or more by depressing the accelerator pedal for at least 10 seconds (Step "E").
(k) Soon after performing step "E" above, release the accelerator pedal for at least 5 seconds without depressing the brake pedal, in order to execute fuel-cut control (Step "F").
(l) Allow the vehicle to decelerate until the vehicle decelerates to less than 10 km/h (6 mph).
(m) Repeat steps "C" through "F" above at least 3 times in one driving cycle (Step "G").
(n) Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.
(o) Read the pending DTCs.

INSPECTION PROCEDURE

Tech Tips

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F sensor operation using the tester.

Connect the intelligent tester to the DLC3.
Start the engine.
Turn the tester on.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the tester.

Tech Tips

The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 (air fuel ratio)	+25%	Rich	Less than 3.1 V
AFS Voltage B1S1 (air fuel ratio)	-12.5%	Lean	More than 3.4 V
O2S B1S2 (heated oxygen)	+25%	Rich	More than 0.55 V
O2S B1S2 (heated oxygen)	-12.5%	Lean	Less than 0.4 V

Note

The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

Case	Air Fuel Ratio Sensor (Sensor 1) Output Voltage	Heated Oxygen Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
1			-
2			Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3			Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4			Fuel pressure Gas leakage from exhaust system (Air fuel ratio extremely lean or rich)

Following the Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / AFS Voltage B1S1 and O2S B1S2; then press the graph button on the Data List screen.

Tech Tips

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
A low air fuel ratio sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A high air fuel ratio sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.

PROCEDURE

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195 OR P2196)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs.

Result

Result	Proceed to
DTC P2195 or P2196 is output	A
DTC P2195, P2196 and P0136, P0137 or P0138 are output	A
DTC P2195 or P2196 and DTCs other than P0136, P0137 and P0138 are output	B

Tech Tips

If any DTCs other than P2195 and P2196 are output, troubleshoot those DTCs first.

GO TO DTC CHART Click here

READ VALUE USING INTELLIGENT TESTER (AIR FUEL RATIO SENSOR CURRENT)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the tester on.
Clear the DTCs Click here.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / AFS Current B1S1.

Check the value of the air fuel ratio sensor output current during fuel-cut, referring to the Monitor Drive Pattern 2 (Detail for Procedure "C" though Procedure "G") in the Confirmation Driving Pattern.

Tech Tips

To measure the air fuel ratio sensor current precisely, perform the fuel-cut operation as long as possible.
If it is difficult to measure the sir fuel ratio sensor current, use the snapshot function of the intelligent tester.

Result

Result	Proceed to
Within normal range (1.0 mA or higher, and below 3.6 mA)	A
Outside normal range (Below 1.0 mA, or 3.6 mA or higher)	B

REPLACE AIR FUEL RATIO SENSOR Click here

READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF AIR FUEL RATIO SENSOR)

Connect the intelligent tester to the DLC3.
Start the engine.
Turn the tester on.
Warm up the air fuel ratio sensor at an engine speed of 2500 rpm for 90 seconds.
Enter the following menus: Powertrain / Engine and ECT / Data List / AFS Voltage B1S1 and Engine Speed, then press the Record button.

Check the air fuel ratio sensor voltage three times, when the engine is in each of the following conditions:

(1) While idling (check for at least 30 seconds)
(2) At an engine speed of approximately 2500 rpm (without any sudden changes in engine speed)
(3) Raise the engine speed to 4000 rpm and then quickly release the accelerator pedal so that the throttle valve is fully closed.

Standard Voltage

Condition

Air Fuel Ratio Sensor Voltage Variation

Reference

(1) and (2)

Changes at approximately 3.3 V

Between 3.1 V and 3.4 V

(3)

Increases to 3.8 V or higher

This occurs during engine deceleration

(when fuel-cut is performed)

Tech Tips

For more information, see the diagrams below.

Tech Tips

If the output voltage of the air fuel ratio sensor remains at approximately 3.3 V (see Malfunction Condition diagram) under any conditions, including those above, the air fuel ratio sensor may have an open circuit. (This will also happen if the air fuel ratio sensor heater has an open circuit.)
If the output voltage of the air fuel ratio sensor remains at either approximately 3.8 V or higher, or below 2.8 V (see Malfunction Condition diagram) under any conditions, including those above, the air fuel ratio sensor may have a short circuit.
The ECM stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and results in a momentary increase in the air fuel ratio sensor output voltage.
When the vehicle is driven:

The output voltage of the air fuel ratio sensor may be below 2.8 V during fuel enrichment. For the vehicle, this translates to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The air fuel ratio sensor is functioning normally.
The air fuel ratio sensor is a current output element; therefore, the current is converted into a voltage inside the ECM. Measuring the voltage at the connectors of the air fuel ratio sensor or ECM will show a constant voltage result.

Click here

PERFORM CONFIRMATION DRIVING PATTERN
1. Connect the intelligent tester to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the tester on.
4. Clear the DTCs.
5. Drive the vehicle referring to the Confirmation Driving Pattern.
NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Check the DTC judgment result.

Result

Result	Proceed to
ABNORMAL (DTC P2195 or P2196 is output)	A
NORMAL (DTC is not output)	B

CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST Click here

REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
NEXT
PERFORM CONFIRMATION DRIVING PATTERN
1. Connect the intelligent tester to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the tester on.
4. Clear the DTCs.
5. Drive the vehicle referring to the Confirmation Driving Pattern.
NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Check the DTC judgment result.

Result

Result	Proceed to
NORMAL (DTC is not output)	A
ABNORMAL (DTC P2195 or P2196 is output)	B

REPLACE ECM Click here

END

CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
1. Has the vehicle run out of fuel in the past?
NO
CHECK FOR INTERMITTENT PROBLEMS Click here

YES

DTC CAUSED BY RUNNING OUT OF FUEL

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Text in Illustration

*1
Component without harness connected

(Air Fuel Ratio Sensor)

Disconnect the air fuel ratio sensor connector.

Text in Illustration
*1	Component without harness connected (Air Fuel Ratio Sensor)

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
1 (HA1A) - 2 (+B)	20°C (68°F)	1.8 to 3.4 Ω
1 (HA1A) - 4 (A1A-)	Always	10 kΩ or higher

Reconnect the air fuel ratio sensor connector.

REPLACE AIR FUEL RATIO SENSOR Click here

CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

Disconnect the air fuel ratio sensor connector.
Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
D54-1 (HA1A) - D41-109 (HA1A)	Always	Below 1 Ω
D54-3 (A1A+) - D41-112 (A1A+)	Always	Below 1 Ω
D54-4 (A1A-) - D41-113 (A1A-)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
D54-1 (HA1A) or D41-109 (HA1A) - Body ground	Always	10 kΩ or higher
D54-3 (A1A+) or D41-112 (A1A+) - Body ground	Always	10 kΩ or higher
D54-4 (A1A-) or D41-113 (A1A-) - Body ground	Always	10 kΩ or higher

Reconnect the air fuel ratio sensor connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leaks Click here.
  
  OK
  
  No leaks in intake system.
NG
REPAIR OR REPLACE INTAKE SYSTEM

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure Click here.
NG
REPAIR OR REPLACE FUEL SYSTEM

OK
INSPECT FUEL INJECTOR ASSEMBLY
1. Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.
NG
REPLACE FUEL INJECTOR ASSEMBLY Click here

OK
REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
NEXT
PERFORM CONFIRMATION DRIVING PATTERN
1. Connect the intelligent tester to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the tester on.
4. Clear the DTCs.
5. Drive the vehicle referring to the Confirmation Driving Pattern.
NEXT

OK
No leaks in intake system.

CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Check the DTC judgment result.

Result

Result	Proceed to
NORMAL (DTC is not output)	A
ABNORMAL (DTC P2195 or P2196 is output)	B

REPLACE ECM Click here

END