P2195

2AZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2195,P2196: Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)

DTC P2195 - Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)

DTC P2196 - Oxygen (A/F) Sensor Signal Stuck Rich (Bank 1 Sensor 1)

CAUTION / NOTICE / HINT
HINT:
- Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
- Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

DESCRIPTION

The A/F sensor generates a voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the ECM (included in the hybrid vehicle control ECU) 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 A/F sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The A/F sensor is a planar type and is integrated with the heater, that 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 air-fuel ratio detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.
A Three-Way Catalytic converter (TWC) is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) into less harmful substances. To allow the TWC to function effectively, it is necessary to keep the air-fuel ratio of the engine near the stoichiometric air-fuel ratio.
*: Value changes inside the ECM. Since the A/F sensor uses a current output element, the current is converted into a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.









HINT:
- When either of these DTCs is set, check the A/F sensor output voltage by selecting the following menu items on the Techstream: Powertrain / Engine / Data List / A/F Control System / AFS B1 S1.
- 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 A/F sensor output voltage cannot be confirmed without using the Techstream.
- If the A/F sensor is malfunctioning, the ECM sets DTC P2195 or P2196.

MONITOR DESCRIPTION

Sensor voltage detection monitor

Under the air-fuel ratio feedback control, if the A/F sensor output voltage indicates rich or lean for a certain period of time, the ECM (included in the hybrid vehicle control ECU) determines that there is a malfunction in the A/F sensor. The ECM illuminates the MIL and sets a DTC.
Example:
If the A/F sensor output voltage is less than 2.8 V (very rich condition) for 10 seconds, despite the rear HO2 sensor output voltage being less than 0.6 V, the ECM sets DTC P2196. Alternatively, if the A/F sensor output voltage is more than 3.8 V (very lean condition) for 10 seconds, despite the rear HO2 sensor output voltage being 0.15 V or more, DTC P2195 is set.

Sensor current detection monitor

A rich air-fuel mixture causes a low A/F sensor current, and a lean air-fuel mixture causes a high A/F 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 A/F sensor current during fuel-cut and detects any abnormal current values.
If the A/F sensor output is 3.6 mA or more for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the A/F sensor and sets DTC P2195 (high-side stuck). If the A/F sensor output is less than 1.0 mA for more than 3 seconds of cumulative time, the ECM sets DTC P2196 (low-side stuck).





MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All:





Sensor voltage detection monitor P2195 and P2196:





Sensor current detection monitor P2195 and P2196:





TYPICAL MALFUNCTION THRESHOLDS

Sensor voltage detection monitor (Lean side malfunction P2195):





Sensor voltage detection monitor (Rich side malfunction P2196):





Sensor current detection monitor (High side malfunction P2195):





Sensor current detection monitor (Rich side malfunction P2196):





MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM





CONFIRMATION DRIVING PATTERN

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








(a) Connect the Techstream to the DLC3 (a).
(b) Turn the power switch on (IG) (b).
(c) Turn the tester on (c).
(d) Clear the DTCs DTC Check / Clear (d).
(e) Put the engine in inspection mode Component Tests and General Diagnostics, warm it up until the ECT reaches 75°C (167°F) or higher (e).
(f) On the Techstream, select the following menu items to check the fuel-cut status: Powertrain / Engine / Data List / Idle Fuel Cut (f).
(g) Drive the vehicle at between 38 mph (60 km/h) and 75 mph (120 km/h) for at least 10 minutes (g).
(h) Change the transmission to the B position (h).
(i) Drive the vehicle at a proper vehicle speed to perform fuel-cut operation (i).
HINT: Fuel-cut is performed when the following conditions are met:
- Accelerator pedal is fully released.
- Engine speed is 2,500 rpm or more (fuel injection resumes at 1,000 rpm).
(j) Accelerate the vehicle to 40 mph (64 km/h) or more by depressing the accelerator pedal for at least 10 seconds (j).
(k) Soon after performing step (j) above, release the accelerator pedal for at least 4 seconds without depressing the brake pedal, in order to execute fuel-cut control (k).
(l) Allow the vehicle to decelerate until the vehicle speed declines to less than 6 mph (10 km/h) (l).
(m) Repeat steps from (h) through (k) above at least 3 times in one driving cycle (m).
HINT: Completion of all A/F sensor monitors is required to change the value in TEST RESULT.
CAUTION: Strictly observe posted speed limits, traffic laws, and road conditions when performing these drive patterns.

INSPECTION PROCEDURE
HINT: The Techstream only:
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 (A/F) sensor, Heated Oxygen (HO2) 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 Techstream.
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Component Tests and General Diagnostics.
(c) Turn the tester on.
(d) Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(e) On the tester, select the following menu items: Powertrain / Engine / Active Test / Control the Injection Volume for A/F sensor.
(f) Perform the Control the Injection Volume for A/F sensor operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
(g) Monitor the output voltages of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2) displayed on the tester.
HINT:
- 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%.
- The sensors react in accordance with increases and decreases in the fuel injection volume.

Standard:





NOTICE: The A/F sensor has an output delay of a few seconds and the HO2 sensor (sensor 2) output has a maximum output delay of approximately of 20 seconds.





- Following the Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
- To display the graph, select the following menu items on the tester: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS B1 S1 and O2S B1 S2 then press the graph button on the Data List view.
HINT:
- DTC P2A00 may be set when the air-fuel ratio is stuck rich or lean.
- Read freeze frame data using the Techstream. The ECM (included in the hybrid vehicle control ECU) records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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 A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
- A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check for conditions that would cause the engine to run lean.

PROCEDURE

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195 OR P2196)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the tester on.
(d) Select the following menu items: Powertrain / Engine / Trouble Code.
(e) Read the DTCs.
Result:





HINT: If any DTCs relating to the A/F sensor (DTCs for the A/F sensor heater or A/F sensor admittance) are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (TEST VALUE OF A/F SENSOR)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG) and turn the tester on.
(c) Clear the DTCs DTC Check / Clear.
(d) Drive the vehicle in accordance with the drive pattern described in CONFIRMATION DRIVING PATTERN.
(e) Select the following menu items: Powertrain / Engine / Monitor / O2 Sensor.
(f) Check that the status of O2S MON is Complete.
If the status is still Incomplete, drive the vehicle according to the driving pattern again.
HINT:
- Complete indicates that the component is functioning normally.
- Incomplete indicates that the component is malfunctioning.
(g) Select the following menu items: Powertrain / Engine / Monitor / O2 Sensor / Details / RANGE B1 S1.
(h) Check the test value of the A/F sensor output current during fuel-cut.
Result:






B -- REPLACE AIR FUEL RATIO SENSOR
A -- Continue to next step.
3. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF A/F SENSOR)
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Component Tests and General Diagnostics.
(c) Turn the tester on.
(d) Warm up the A/F sensor at an engine speed of 2,500 rpm for 90 seconds.
(e) On the tester, select the following menu items: Powertrain / Engine / Data List / A/F Control System / AFS B1 S1 and Engine Speed, then press the Record button.
(f) Check the A/F sensor voltage 3 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 2,500 rpm (without any sudden changes in engine speed)
- (3) Drive the vehicle at a constant speed of between 40 mph and 70 mph (65 km/h and 113 km/h) and then quickly release the accelerator pedal so that the throttle valve is fully closed.
Standard voltage:





HINT:
- For more information, see the diagrams below.




- If the output voltage of the A/F sensor remains at approximately 3.3 V (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor may have an open circuit. (This will also happen if the A/F sensor heater has an open circuit.)
- If the output voltage of the A/F sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see Malfunction Condition diagram) under any conditions, including those above, the A/F 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 A/F sensor output voltage.
- The ECM must establish a closed throttle valve position learning value to perform fuel cut. If the battery terminal has been reconnected, the vehicle must be driven over 10 mph (16 km/h) to allow the ECM to learn the closed throttle valve position.
- When the vehicle is driven:
The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. For the vehicle, this is translated to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/F sensor is functioning normally.
- The A/F 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 A/F sensor or ECM will show a constant voltage result.

NG -- INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
OK -- Continue to next step.
4. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
5. CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)
(a) Select the following menu items: Powertrain / Engine / Trouble Code / Pending.
(b) Read the DTCs using the Techstream.
Result:






B -- END
A -- Continue to next step.
6. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor Removal.
NEXT -- Continue to next step.
7. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
8. CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)
(a) Select the following menu items: Powertrain / Engine / Trouble Code / Pending.
(b) Read the DTCs using the Techstream.
Result:






B -- REPLACE HYBRID VEHICLE CONTROL ECU
A -- END
9. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) P0031
NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- Continue to next step.
10. INSPECT INTEGRATION RELAY (EFI RELAY) P0031
NG -- REPLACE INTEGRATION RELAY (EFI MAIN RELAY)
OK -- Continue to next step.
11. CHECK HARNESS AND CONNECTOR (A/F SENSOR - HYBRID VEHICLE CONTROL ECU)




(a) Disconnect the C15 A/F sensor connector.
(b) Turn the power switch on (IG).
(c) Measure the voltage between the +B terminal of the A/F sensor connector and body ground.
Standard voltage:





(d) Turn the power switch off.
(e) Disconnect the C64 hybrid vehicle control ECU connector.
(f) Measure the resistance.
Standard resistance (Check for open):






Standard resistance (Check for short):





(g) Reconnect the hybrid vehicle control ECU connector.
(h) Reconnect the A/F sensor connector.





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
12. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor Removal.
NEXT -- Continue to next step.
13. PERFORM CONFIRMATION DRIVING PATTERN
NEXT -- Continue to next step.
14. CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)
(a) Select the following menu items: Powertrain / Engine / Trouble Code / Pending.
(b) Read the DTCs using the Techstream.
Result:






B -- REPLACE HYBRID VEHICLE CONTROL ECU
A -- END