Troubleshooting
DTC P0150 OXYGEN SENSOR CIRCUIT MALFUNCTION (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.
If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is LEAN. The HO2S voltage drops below 0.45 V and the HO2S informs the ECM of the LEAN condition.
If oxygen is not in the exhaust gas, the air-fuel ratio is RICH. The HO2S voltage increases above 0.45 V and the HO2S 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:
O2S Test Result:
The Engine Control Module (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.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
a. Connect the hand-held tester to the DLC3.
b. Switch from normal mode to check mode.
c. Allow the engine to idle until the Engine Coolant Temperature (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. Perform steps (d) and (e) at least 3 times.
f. Allow the engine to idle for 30 seconds.
HINT: If a malfunction exists, the Malfunction Indicator Light (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 (f), then perform steps from (c) to (f) again.
Step 1:
Step 2 - 3:
Step 4 - 6:
Step 7 - 10:
INSPECTION PROCEDURE
HINT: Narrowing down the trouble area is possible by performing the A/F CONTROL on the Active Test (HO2S or other trouble areas can be distinguished).
The injection volume can be switched to -12.5 % (decrease) or +25 % (increase) by A/F CONTROL.
The A/F CONTROL procedure enables a technician to check and graph the voltage outputs of the HO2Ss.
A/F CONTROL Procedure:
a. Connect the hand-held tester to the DLC3 on the vehicle.
b. Turn the ignition switch ON.
c. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
d. Select the item "DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL".
e. Perform A/F CONTROL at the engine idling.
Standard:
The HO2S reacts in accordance with 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 front HO2S output has a few seconds of delay and the rear HO2S 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.