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

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.

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.

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 more than 3.8 V (b) Heated oxygen sensor voltage is 0.21 V or more	Open or short in air fuel ratio sensor (bank 1 sensor 1) circuit Air fuel ratio sensor (bank 1 sensor 1) Air fuel ratio sensor (bank 1 sensor 1) heater Air fuel ratio sensor heater circuit Intake system Exhaust system Fuel line Fuel pressure Fuel injector assembly EGR valve assembly ECM
P2195	While fuel-cut operation performed (during vehicle deceleration), air fuel ratio sensor current is 2.2 mA or more for 3 seconds (2 trip detection logic)	Air fuel ratio sensor (bank 1 sensor 1) ECM
P2196	Conditions (a) and (b) continue for 10 seconds or more (2 trip detection logic) (a) Air fuel ratio sensor voltage less than 2.8 V (b) Heated oxygen sensor voltage is below 0.69 V	Open or short in air fuel ratio sensor (bank 1 sensor 1) circuit Air fuel ratio sensor (bank 1 sensor 1) Air fuel ratio sensor (bank 1 sensor 1) heater Air fuel ratio sensor heater circuit Intake system Exhaust system Fuel line Fuel pressure Fuel injector assembly EGR valve assembly ECM
P2196	While fuel-cut operation performed (during vehicle deceleration), air fuel ratio sensor current is less than 0.7 mA for 3 seconds (2 trip detection logic)	Air fuel ratio sensor (bank 1 sensor 1) ECM

Tech Tips

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

MONITOR DESCRIPTION

Sensor voltage detection monitor
Under air-fuel ratio feedback control, If the air fuel ratio sensor output voltage is below 2.8 V (very rich condition) for 5 seconds despite the rear heated oxygen sensor output voltage being below 0.69 V, the ECM stores DTC P2196. Alternatively, if the air fuel ratio sensor output voltage is higher than 3.8 V (very lean condition) for 5 seconds despite the rear heated oxygen sensor output voltage being 0.21 V or higher, DTC P2195 is stored.

Sensor current detection monitor
A rich air-fuel mixture causes a low air fuel ratio sensor current, and a lean air-fuel mixture causes a high air fuel ratio sensor current. Therefore, the sensor output becomes low during acceleration, and it becomes high during deceleration with the throttle valve fully closed. The ECM monitors the air fuel ratio sensor current during fuel-cut and detects any abnormal current values.

If the air fuel ratio sensor output is 2.2 mA or higher for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the air fuel ratio sensor and stores DTC P2195 (stuck on high side). If the air fuel ratio sensor output is below 1.4 mA for more than 3 seconds of cumulative time, the ECM stores DTC P2196 (stuck on low side).

CONFIRMATION DRIVING PATTERN

This confirmation driving pattern is used in the "Perform Confirmation Driving Pattern" procedure of the following diagnostic troubleshooting procedure.

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on.
Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the tester on.
Start the engine and warm it up until the ECT reaches 75°C (167°F) or higher [A].
On the tester, enter the following menus to check the fuel-cut status: Powertrain / Engine and ECT / Data List / Idle Fuel Cut.
Drive the vehicle at a speed between 60 and 100 km/h (37 and 63 mph) for at least 10 minutes [B].

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Shift the transmission to 2nd gear [C].
Accelerate the vehicle to 60 km/h (37 mph) or more by depressing the accelerator pedal for at least 30 seconds [D].

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Soon after performing step [D] above, release the accelerator pedal for at least 4 seconds without depressing the brake pedal in order to execute fuel-cut control [E].
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 1000 rpm).
Allow the vehicle to decelerate until the vehicle speed decreases to less than 10 km/h (6 mph).
Repeat steps [C] through [E] above at least 3 times in one driving cycle.
Enter the following menus: Powertrain / Engine and ECT / DTC [F].
Read the pending DTCs.
Tech Tips
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P2195 or P2196.

Check the DTC judgment result.

Tester Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
UNKNOWN	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

Tech Tips

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] through [F] again.

WIRING DIAGRAM

Refer to DTC P0031 Click here.

CAUTION / NOTICE / HINT

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 (TWC) and located near the engine assembly.
DTC P2A00 may be stored when the air-fuel ratio is stuck at a rich or lean value.
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
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.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.

PROCEDURE

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

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
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 or P2196 and P0136, P0137 or P0138 are output	A
DTC P2195 or P2196 and other DTCs 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

CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
1. Has the vehicle run out of fuel in the past?
NO
READ VALUE USING INTELLIGENT TESTER (AFS CURRENT) Click here

YES

PERFORM CONFIRMATION DRIVING PATTERN

Perform the confirmation driving pattern.

Tech Tips

Refer to the Confirmation Driving Pattern.

Result
Result	Proceed to
NORMAL (No DTC outputs)	A
ABNORMAL (DTC P2195 or P2196 outputs)	B

DTC CAUSED BY RUNNING OUT OF FUEL

READ VALUE USING INTELLIGENT TESTER (AFS CURRENT)

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

Check the test value of the air fuel ratio sensor output current during fuel-cut, referring to the Monitor Driving Pattern 2 (Detail for Procedure "C" through 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 air fuel ratio sensor current, use the snapshot function of the intelligent tester.

Result
Result	Proceed to
Within normal range (1.57 mA or more, and less than 3.6 mA)	A
Outside normal range (Less than 1.57 mA, or 3.6 mA or more)	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 / Active Test / Control the Injection Volume.
Perform the Control the Injection Volume operation with the engine idling.

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

Change the fuel injection volume within the range of -12.0% to +12.0%. The injection volume can be changed in fine gradations.
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.

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 (Air fuel ratio)	+12%	Rich	Below 3.1 V
AFS Voltage B1S1 (Air fuel ratio)	-12%	Lean	Higher than 3.4 V
O2S B1S2 (Heated oxygen)	+12%	Rich	Higher than 0.55 V
O2S B1S2 (Heated oxygen)	-12%	Lean	Below 0.4 V

Result
Status of AFS Voltage B1S1	Status of O2S B1S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition	Proceed to
Lean	Lean	Actual air fuel ratio lean	A
Rich	Rich	Actual air fuel ratio rich	A
Lean	Lean/Rich	Air fuel ratio sensor malfunction	B
Rich	Lean/Rich	Air fuel ratio sensor malfunction	B
Lean/Rich	Lean/Rich	Normal	C

Lean: During the Control the Injection Volume Active Test, the air fuel ratio sensor output voltage (AFS Voltage) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S) is consistently below 0.4 V.

Rich: During the Control the Injection Volume Active Test, the AFS Voltage is consistently below 3.1 V, and the O2S is consistently higher than 0.55 V.

Lean/Rich: During the Control the Injection Volume Active Test, the output voltage of the air fuel ratio or heated oxygen sensor alternates correctly.

Tech Tips

Refer to "Data List / Active Test" [AFS Voltage B1S1, O2S B1S2] Click here.

REPLACE AIR FUEL RATIO SENSOR Click here

CHECK FOR INTERMITTENT PROBLEMS Click here

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

OK
CHECK FOR EXHAUST GAS LEAK
1. Check for exhaust gas leaks.
  
  OK
  
  No gas leaks.
NG
REPAIR OR REPLACE EXHAUST SYSTEM

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure Click here.
NG
CHECK FUEL LINE Click here

OK
INSPECT FUEL INJECTOR ASSEMBLY
1. Check the fuel injector injection (whether fuel volume is high or low, and whether injection pattern is poor) Click here.
  
  Tech Tips
  
  Perform "Inspection After Repairs" after replacing the fuel injector assembly Click here.
NG
REPLACE FUEL INJECTOR ASSEMBLY Click here

OK
REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
  
  Tech Tips
  
  Perform "Inspection After Repairs" after replacing the air fuel ratio sensor Click here.
NEXT

OK
No leak from intake system.

OK
No gas leaks.

CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Perform the confirmation driving pattern.

Tech Tips

Refer to the Confirmation Driving Pattern.

Result
Result	Proceed to
ABNORMAL (DTC P2195 or P2196 outputs)	A
NORMAL (No DTC outputs)	B

END

READ VALUE USING INTELLIGENT TESTER (CONTROL THE EGR STEP POSITION)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the tester on.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.

Tech Tips

The A/C switch and all accessory switches should be off.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

Check the engine idling condition in the Data List while performing the Active Test.

EGR Step Position

(Active Test)

Specified Condition

0 Steps

Steady idling

0 to 30 Steps

Idling changes from steady to rough idling

Tech Tips

Do not leave the EGR valve open for 10 seconds or more during the Active Test.
Be sure to return the EGR valve to step 0 when the Active Test is completed.

Result
Result	Proceed to
Outside of standard range	A
Within standard range	B

REPLACE ECM Click here

INSPECT EGR VALVE ASSEMBLY
1. Remove the EGR valve assembly Click here.
2. Check for contamination between the EGR valve and housing.
  
  OK
  
  EGR valve is not contaminated with foreign objects.
3. Reinstall the EGR valve assembly Click here.
NG
REPLACE EGR VALVE ASSEMBLY Click here

OK
REPLACE ECM
1. Replace the ECM Click here.
NEXT
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED
1. Perform the confirmation driving pattern.
  
  Tech Tips
  
  Refer to the CONFIRMATION DRIVING PATTERN.
NEXT
END
REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
  
  Tech Tips
  
  Perform "Inspection After Repairs" after replacing the air fuel ratio sensor Click here.
NEXT

OK
EGR valve is not contaminated with foreign objects.

CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Perform the confirmation driving pattern.

Tech Tips

Refer to the Confirmation Driving Pattern.

Result
Result	Proceed to
NORMAL	A
ABNORMAL	B

END

REPLACE ECM Click here

CHECK FUEL LINE
1. Check the fuel lines for leaks or blockage.
OK
REPLACE FUEL PUMP Click here

NG
REPAIR OR REPLACE FUEL LINE