P2198
DTC P2198 OXYGEN SENSOR SIGNAL STUCK RICH (BANK 2 SENSOR 1)HINT:
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that does not include cylinder No. 1.
- Bank 1 includes cylinder No. 1, but bank 2 does not. Cylinder No. 1 is located in the front part of the engine, opposite the transmission.
- Sensor 1 refers to the sensor closest to the engine body.
- Sensor 2 refers to the sensor farthest away from the engine body.
CIRCUIT DESCRIPTION
DTC Detection Condition:
The Heated Oxygen Sensor (HO2S) is used to monitor oxygen concentration in the exhaust gas. For optimum catalytic converter operation, the air-fuel mixture must be maintained near the ideal stoichiometric ratio. The HO2S 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.The HO2S generates a voltage between 0.1 and 0.9 V in response to oxygen concentration in the exhaust gas.
If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is called LEAN. The HO2S voltage drops below 0.45 V, which informs the ECM of the LEAN condition.
If oxygen is not in the exhaust gas, the air-fuel ratio is called RICH. The HO2S voltage increases above 0.45 V, which informs the ECM of the RICH condition.
HINT: The ECM provides a pulse width modulated control circuit to adjust current through the heater. The HO2S heater circuit uses a relay on the +B side of the circuit.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
The ECM uses the HO2S information to regulate the air-fuel ratio close to a stoichiometric ratio. This maximizes the catalytic converter's ability to purify the exhaust gases. The HO2S 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 gases. The sensor element is made of platinum coated zirconia and includes an integrated heating element. The HO2S's output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. The HO2S generates output voltage between 0.1 V and 0.9 V in response to the oxygen concentration in exhaust gas. When the front HO2S voltage 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.
The HO2S should indicate RICH and LEAN alternately at a regular cycle under the air-fuel ratio feedback control. If the HO2S voltage remains at RICH or LEAN for about 20 seconds, the ECM interprets this as malfunction of the HO2S. The ECM illuminates MIL (2 trip detection logic.and sets a DTC.
O2S TEST RESULT
O2S Test Result:
The O2S Test Result (mode 05) allows the OBD II scan tool to display the test value that was used to determine whether the Heated Oxygen Sensor (HO2S) is functioning normally or not. The HO2S condition can be checked by comparing the test value and the malfunction criterion. This procedure is described in "O2S TEST RESULT".
- TID (Test Identification Data. is assigned to each test value.
- Unit Conversion is used to calculate the test value.
CONFIRMATION DRIVING PATTERN
a. Connect the hand-held tester to the DLC3.
b. Switch the hand-held tester from normal mode to check mode
c. Allow the engine to idle until the ECT reaches 75 °C (167 °F).
d. Allow the vehicle to run at 40 km/h (25 mph) or more for 25 seconds or more.
e. Allow the engine to idle for 30 seconds or more.
f. Perform steps d.and e.at least 3 times.
g. Allow the engine to idle for 30 seconds.
HINT: If a malfunction exists, the MIL will be illuminated on the multi-information display during step (f).
NOTE: If the conditions in this test are not strictly followed, you should perform steps d.and e.. If you do not have the hand-held tester, turn the ignition switch OFF after performing steps from (c) to (g), then perform steps from (c) to (g) again.
Wiring Diagram:
Step 1:
Step 2 - 3:
Step 4 - 6:
Step 7 - 10:
INSPECTION PROCEDURE
HINT: It is possible the malfunctioning area can be found using the ACTIVE TEST A/F CONTROL operation. The ACTIVE TEST can determine if the HO2S or other potential trouble areas are malfunctioning or not. The injection volume can be switched to -12.5 % (decrease.or +25 % (increase.by the ACTIVE TEST. The ACTIVE TEST procedure enables a technician to check and graph the voltage outputs of the HO2Ss.
Procedure:
a. Connect the hand-held tester to the DLC3.
b. Turn the ignition switch ON.
c. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
d. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
e. Perform the ACTIVE TEST while the engine is idling.
Standard:
The HO2S reacts in accordance with the increase and decrease of injection volume:
+25 % "->RICH output: more than 0.55 V
-12.5 % "->LEAN output: Less than 0.4 V
NOTE: The HO2S (sensor 1.output has a few seconds of delay and the HO2S (sensor 2.output has a maximum of 20 seconds of delay.
If the vehicle is short of fuel, the air-fuel ratio becomes LEAN and the DTCs will be recorded.
HINT: Read freeze frame data using the hand-held tester. Freeze frame data records the engine conditions when a malfunction is detected.When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.
CHECK FOR INTERMITTENT PROBLEMS
HINT: Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the hand-held tester is in check mode. In check mode, the hand-held tester uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default), which uses 2 trip detection logic.
a. Clear the DTCs.
b. Set the check mode.
c. Perform a simulation test.
d. Check the connector and terminal.
e. Wiggle the harness and the connector.