- Open or short in A/F sensor (for Sensor 1) circuit
- A/F sensor (for Sensor 1)
- A/F sensor heater (for Sensor 1)
- Integration relay
- A/F sensor heater and integration relay circuits
- Air induction system
- Fuel pressure
- Injector
- ECM
| Last Modified: 11-29-2007 | 1.6 C | |
| Service Category: Engine/Hybrid System | Section: Engine Control | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM000000WC405UX |
| Title: 3UR-FE ENGINE CONTROL: SFI SYSTEM: CAUTION / NOTICE / HINT (2008 Sequoia) | ||
|
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) |
|
DTC |
P2197 |
Oxygen (A/F) Sensor Signal Stuck Lean (Bank 2 Sensor 1) |
|
DTC |
P2198 |
Oxygen (A/F) Sensor Signal Stuck Rich (Bank 2 Sensor 1) |
CAUTION / NOTICE / HINT
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 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 A/F sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The A/F 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 air-fuel ratio 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 TWC is used. For the most efficient use of the TWC, 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 A/F sensor is the current output element, a 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.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P2195 P2197 |
Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic): (a) A/F sensor voltage more than 3.8 V for 5 seconds (b) Heated Oxygen (HO2) sensor voltage 0.21 V or more |
|
|
While fuel-cut operation performed (during vehicle deceleration), A/F sensor current 3.6 mA or more for 3 seconds (2 trip detection logic) |
|
|
|
P2196 P2198 |
Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic): (a) A/F sensor voltage less than 2.8 V for 5 seconds (b) HO2 sensor voltage less than 0.59 V |
|
|
While fuel-cut operation performed (during vehicle deceleration), A/F sensor current less than 1.4 mA for 3 seconds (2 trip detection logic) |
|
HINT:
- DTCs P2195 and P2196 indicate malfunctions related to bank 1 A/F sensor circuit.
- DTCs P2197 and P2198 indicate malfunctions related to bank 2 A/F sensor circuit.
- Bank 1 refers to the bank that includes No. 1 cylinder.
- Bank 2 refers to the bank that includes No. 2 cylinder.
- When either of these DTCs is stored, check the A/F sensor output voltage by entering the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / AFS B1 S1 or AFS B2 S1.
- Short-term fuel trim values can also be read using the Techstream.
- The ECM regulates the voltages at the A1A+ and A1A- or A2A+ and A2A- 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 stores the DTC P2195, P2196, P2197 or P2198.
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 determines that there is a malfunction in the A/F sensor. The ECM illuminates the MIL and stores a DTC.
Example:
If the A/F sensor output voltage is less than 2.8 V (very rich condition) for 5 seconds, despite the rear HO2 sensor output voltage being less than 0.59 V, the ECM stores DTC P2196 or P2198. Alternatively, if the A/F sensor output voltage is more than 3.8 V (very lean condition) for 5 seconds despite the rear HO2 sensor output voltage being 0.21 V or more, DTC P2195 or P2197 is stored.
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 stores DTC P2195 or P2197 (high-side stuck). If the A/F sensor output is less than 1.4 mA for more than 3 seconds of cumulative time, the ECM stores DTC P2196 or P2198 (low-side stuck).
MONITOR STRATEGY
|
Related DTCs |
P2195: A/F sensor signal stuck lean (Bank 1) P2196: A/F sensor signal stuck rich (Bank 1) P2197: A/F sensor signal stuck lean (Bank 2) P2198: A/F sensor signal stuck rich (Bank 2) |
|
Required Sensors/Components (Main) |
A/F sensor |
|
Required Sensors/Components (Related) |
HO2 sensor |
|
Frequency of Operation |
Continuous |
|
Duration |
5 seconds: Sensor voltage detection monitor 3 seconds: Sensor current detection monitor |
|
MIL Operation |
2 driving cycles |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
All
|
Monitor runs whenever following DTCs not present |
P0031, P0032, P0051, P0052 (A/F Sensor Heater - Sensor 1) P0037, P0038, P0057, P0058 (O2 Sensor Heater - Sensor 2) P0102 - P0103 (MAF meter) P0110 - P0113 (IAT sensor) P0115 - P0118 (ECT sensor) P0120 - P0223, P2135 (TP sensor) P0125 (Insufficient ECT for Closed Loop) P0136, P0156 (O2 Sensor - Sensor 2) P0171, P0172 (Fuel system) P0300 - P0308 (Misfire) P0335 (CKP sensor) P0455, P0456 (EVAP system) P0500 (VSS) P2440 (AIR control valve stuck open) P2441 (AIR control valve stuck close) P2444 (AIP stuck On) P2445 (AIP stuck Off) |
Sensor Voltage Detection Monitor
|
Time after engine start |
30 seconds or more |
|
Fuel system status |
Closed-loop |
Sensor Current Detection Monitor
|
Battery voltage |
11 V or more |
|
Atmospheric pressure |
76 kPa (570 mmHg) or more |
|
A/F sensor status |
Activated |
|
Continuous time of fuel cut |
3 to 10 seconds |
|
ECT |
75°C (167°F) or more |
TYPICAL MALFUNCTION THRESHOLDS
Sensor Voltage Detection Monitor (Lean Side Malfunction P2195 and P2197)
|
Rear HO2S voltage |
Rises from less than 0.21 V to 0.59 V or more |
|
A/F sensor voltage |
More than 3.8 V for 5 seconds |
Sensor Voltage Detection Monitor (Rich Side Malfunction P2196 and P2198)
|
Rear HO2S voltage |
Falls from 0.59 V or more to less than 0.21 V |
|
A/F sensor voltage |
Less than 2.8 V for 5 seconds |
Sensor Current Detection Monitor (High Side Malfunction P2195 and P2197)
|
A/F sensor current |
3.6 mA or more |
Sensor Current Detection Monitor (Rich Side Malfunction P2196 and P2198)
|
A/F sensor current |
Less than 1.4 mA |
MONITOR RESULT
Refer to Checking Monitor Status
.
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
HINT:
- This confirmation driving pattern is used in the "Perform Confirmation Driving Pattern" procedure of the following diagnostic troubleshooting procedure.
- Performing this confirmation driving pattern will activate the Heated Oxygen (HO2) sensor monitor. (The catalyst monitor is performed simultaneously.) This is very useful for verifying the completion of a repair.
NOTICE:
This test will not be completed if the vehicle is driven under absolutely constant speed conditions such as with cruise control activated.
- Connect the Techstream to the DLC3.
- Turn the ignition switch to ON.
- Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more [A].
- Drive the vehicle at between 60 km/h and 120 km/h (40 mph and 75 mph) for at least 10 minutes [B].
- Drive the vehicle 60 km/h (40 mph) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times [C].
- Turn the Techstream on.
- Enter the following menus: Powertrain / Engine / Utility / All Readiness.
- Input DTCs: P2195, P2196, P2197 and P2198.
- Check the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the drive pattern increasing the vehicle speed and using the second gear to decelerate the vehicle.
INSPECTION PROCEDURE
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.
- DTC P2A00 may be set when the air-fuel ratio is stuck rich or lean.
- Read freeze frame data using the Techstream. 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 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.
HINT:
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) Start the engine.
(c) Turn the Techstream on.
(d) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(e) Enter the following menus: Powertrain / Engine and ECT / 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 or AFS B2 S1 and O2S B2 S2) displayed on the Techstream.
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:
|
Tester Display (Sensor) |
Injection Volume |
Status |
Voltage |
|---|---|---|---|
|
AFS B1 S1 (A/F) |
+25% |
Rich |
Less than 3.0 |
|
-12.5% |
Lean |
More than 3.35 |
|
|
O2S B1 S2 (HO2) |
+25% |
Rich |
More than 0.55 |
|
-12.5% |
Lean |
Less than 0.4 |
|
|
AFS B2 S1 (A/F) |
+25% |
Rich |
Less than 3.0 |
|
-12.5% |
Lean |
More than 3.35 |
|
|
O2S B2 S2 (HO2) |
+25% |
Rich |
More than 0.55 |
|
-12.5% |
Lean |
Less than 0.4 |
NOTICE:
The A/F sensor has an output delay of a few seconds and the HO2 sensor (for Sensor 2) output has a maximum output delay of approximately 20 seconds.
|
Case |
A/F Sensor (Sensor 1) Output Voltage |
HO2 Sensor (Sensor 2) Output Voltage |
Main Suspected Trouble Area |
|---|---|---|---|
|
1 |
|
|
- |
|
2 |
|
|
|
|
3 |
|
|
|
|
4 |
|
|
|
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, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/ F Sensor / A/F Control System / AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2.
PROCEDURE
|
1. |
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195, P2196, P2197 OR P2198) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
P2195, P2196, P2197 or P2198 is output |
A |
|
P2195, P2196, P2197 or P2198 and other DTCs are output |
B |
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.
|
|
2. |
READ VALUE USING TECHSTREAM (TEST VALUE OF A/F SENSOR) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear DTCs
.
(e) Allow the vehicle to drive in accordance with the drive pattern described in the CONFIRMATION DRIVING PATTERN.
(f) Enter the following menus: Powertrain / Engine and ECT / Monitor / O2 Sensor.
(1) Check that the status of O2 Sensor is Complete. If the status is still Incomplete, drive the vehicle according to the driving pattern again.
(g) Enter the following menus: Powertrain / Engine and ECT / Monitor / O2 Sensor / Details / RANGE B1 S1.
(h) Check the test value of the A/F sensor output current during fuel-cut.
Result
|
Test Value |
Proceed to |
|---|---|
|
Within normal range (1.4 mA or more, and less than 3.6 mA) |
A |
|
Outside normal range (Less than 1.4 mA, or 3.6 mA or more) |
B |
|
|
3. |
READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF A/F SENSOR) |
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Warm up the A/F sensor at an engine speed of 2500 rpm for 90 seconds.
(e) On the Techstream, enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / Snapshot / AFS B1 S1 or AFS B2 S1 and Engine Speed.
(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 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 |
A/F Sensor Voltage Variation |
Reference |
|---|---|---|
|
(1) and (2) |
Remains at approximately 3.3 V |
3.1 V to 3.5 V |
|
(3) |
Increases to 3.8 V or more |
This occurs during engine deceleration (when fuel-cut performed) |
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 16 km/h (10 mph) 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 translates 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.
|
|
4. |
PERFORM CONFIRMATION DRIVING PATTERN |
|
|
5. |
CHECK WHETHER DTC OUTPUT RECURS (DTC P2195, P2196, P2197 OR P2198) |
(a) Read DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
(c) Read pending DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
P2195, P2196, P2197 or P2198 is output |
A |
|
No DTC is output |
B |
|
|
6. |
REPLACE AIR FUEL RATIO SENSOR |
(a) Replace the air fuel ratio sensor
.
|
|
7. |
PERFORM CONFIRMATION DRIVING PATTERN |
|
|
8. |
CHECK WHETHER DTC OUTPUT RECURS (DTC P2195, P2196, P2197 OR P2198) |
(a) Read DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
(c) Read pending DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
No DTC is output |
A |
|
P2195, P2196, P2197 or P2198 is output |
B |
|
|
9. |
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
|
|
|
10. |
INSPECT INTEGRATION RELAY (A/F)
|
|
|
11. |
CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM) |
(a) Disconnect the A/F sensor connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
D19-2 (+B) - Body ground |
Ignition switch ON |
11 to 14 V |
|
D20-2 (+B) - Body ground |
Ignition switch ON |
11 to 14 V |
(d) Turn the ignition switch off.
(e) Disconnect the ECM connector.
(f) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
D19-1 (HA1A) - D56-22 (HA1A) |
Always |
Below 1 Ω |
|
D19-3 (A1A+) - D56-126 (A1A+) |
Always |
Below 1 Ω |
|
D19-4 (A1A-) - D56-125 (A1A-) |
Always |
Below 1 Ω |
|
D20-1 (HA2A) - D56-20 (HA2A) |
Always |
Below 1 Ω |
|
D20-3 (A2A+) - D56-103 (A2A+) |
Always |
Below 1 Ω |
|
D20-4 (A2A-) - D56-102 (A2A-) |
Always |
Below 1 Ω |
|
D19-1 (HA1A) or D56-22 (HA1A) - Body ground |
Always |
10 kΩ or higher |
|
D19-3 (A1A+) or D56-126 (A1A+) - Body ground |
Always |
10 kΩ or higher |
|
D19-4 (A1A-) or D56-125 (A1A-) - Body ground |
Always |
10 kΩ or higher |
|
D20-1 (HA2A) or D56-20 (HA2A) - Body ground |
Always |
10 kΩ or higher |
|
D20-3 (A2A+) or D56-103 (A2A+) - Body ground |
Always |
10 kΩ or higher |
|
D20-4 (A2A-) or D56-102 (A2A-) - Body ground |
Always |
10 kΩ or higher |
|
|
12. |
REPLACE AIR FUEL RATIO SENSOR |
(a) Replace the air fuel ratio sensor
.
|
|
13. |
PERFORM CONFIRMATION DRIVING PATTERN |
|
|
14. |
CHECK WHETHER DTC OUTPUT RECURS (DTC P2195, P2196, P2197 OR P2198) |
(a) Read DTCs using the Techstream.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
(c) Read pending DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
No DTC is output |
A |
|
P2195, P2196, P2197 or P2198 is output |
B |
|
|
|