P2196
DTC P2196 Oxygen Sensor Signal Stuck Rich (Bank 1 Sensor 1)CIRCUIT DESCRIPTION
DTC Detection Condition:
The front Heated Oxygen (HO2) sensor is used to monitor oxygen concentration in the exhaust gas. For optimum operation of the TWC, the air-fuel mixture must be maintained near the stoichiometric level. The HO2 sensor output voltage changes suddenly in the vicinity of the stoichiometric ratio. The ECM adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric level.
If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is LEAN. The HO2 sensor voltage drops below 0.45 V and the sensor informs the ECM of the LEAN condition. If oxygen is not in the exhaust gas, the air-fuel ratio is RICH. The sensor voltage increases above 0.45 V and the sensor informs the ECM of the RICH condition.
HINT:
- Sensor 1 refers to the sensor closest to the engine body.
- The output voltage of the heated oxygen sensor and the short-term fuel trim value can be read using the hand-held tester or the OBD II scan tool.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
O2S Test Result (Mode 05 Data):
The ECM uses the oxygen sensor information to regulate the air-fuel ratio close to a stoichiometric ratio. This maximizes the catalytic converter's ability to purify the exhaust gas. The sensor detects oxygen levels in the exhaust gas and sends this signal to the ECM.
The inner surface of the sensor element is exposed to outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum coated zirconia and includes an integrated heating element. The heated oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. The heated oxygen sensor generates output voltage between 0 V and 1.0 V in response to the oxygen concentration in exhaust gas. When the output voltage of the sensor is 0.55 V or more, the ECM judges that the air-fuel ratio is RICH. When it is 0.4 V or less, the ECM judges that the air-fuel ratio is LEAN.
In the normal condition, the heated oxygen sensor indicates RICH and LEAN alternately with a regular cycle under the air-fuel ratio feedback control. If the sensor voltage output remains at RICH, or at LEAN, the ECM interprets this as malfunction of the sensor and sets a DTC.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
Confirmation Driving Pattern:
a. Connect the hand-held tester to the DLC3.
b. Switch the ECM from normal mode to check mode.
c. Allow the engine to idle until the engine coolant temperature reaches 75 °C (167 °F).
d. Drive the vehicle at 40 km/h (25 mph) or more for 35 seconds or more.
e. Allow the engine to idle for 40 seconds or more. Perform steps (d) and (e) at least 3 times.
f. Allow the engine to idle for 40 seconds.
HINT: If a malfunction exists, the MIL is illuminated on the multi information display during step (f).
NOTE: If the conditions in this test are not strictly followed, no malfunction will be occurred.
If you do not have the hand-held tester, turn the ignition switch to OFF after performing steps from (c) to (f), then perform steps from (c) to (f) again.
INSPECTION PROCEDURE
Step 1:
Step 2 - 3:
Step 4:
Step 5:
Step 6 - 9:
Step 10 - 11:
HINT:
Hand-held tester only:
Malfunctioning areas can be found by performing the ACTIVE TEST / A/F CONTROL operation (Heated Oxygen [HO2] sensor or other trouble areas). The A/F CONTROL operation can determine whether the front HO2 sensor (sensor 1), rear HO2 sensor (sensor 2) and other potential trouble areas are malfunctioning or not.
a. Perform A/F CONTROL using the hand-held tester.
HINT: The A/F Control operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
1. Connect the hand-held tester to the DLC3.
2. Turn the ignition switch to ON and turn the hand-held tester ON.
3. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
4. On the hand-held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
5. Perform the A/F CONTROL operation with the engine in an idling condition (press the right or left button).
Result: The heated oxygen sensor reacts in accordance with increase and decrease of the fuel injection volume.
+25 % -> Rich output: More than 0.55 V (sensor 1), More than 0.5 V (sensor 2)
-12.5 % -> Lean output: Less than 0.4 V
NOTE: The front heated oxygen sensor has an output delay of a few seconds and the rear heated oxygen sensor has a maximum output delay of approximately 20 seconds.
Following A/F CONTROL procedure enables the technician to check and graph the voltage outputs of both front and rear heated oxygen sensors.
To display the graph, enter ACTIVE TEST/A/F CONTROL / USER DATA, select "O2S B1S1 and O2S B1S2" by pressing the "YES" button followed by the "ENTER" button and then the "F4" button.
NOTE: If the vehicle is short of fuel, the air-fuel ratio becomes LEAN and heated oxygen sensor DTCs are set, and the MIL then comes on.
HINT:
- If different DTCs related to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- Read freeze frame data using the hand-held tester. Freeze frame data record 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 high Heated Oxygen (HO2) sensor (sensor 1) voltage (0.55 V or more) could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
- A low HO2 sensor (sensor 1) voltage (0.4 V or less) could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.
CHECK FOR INTERMITTENT PROBLEMS
HINT:
Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect with the hand-held tester when the ECM is in check mode. In check mode, the ECM uses 1trip detection logic, which is more sensitive to malfunctions than normal mode (default) that uses 2trip detection logic.
a. Clear DTCs.
b. Switch the ECM from normal mode to check mode using a hand-held tester.
c. Perform a simulation test.
d. Check and wiggle the harness(es), the connector(s) and terminal(s).