Troubleshooting
DTC P0154 OXYGEN SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 2 SENSOR 1)CIRCUIT DESCRIPTION
DTC Detecting 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.
HINT: After confirming DTC P0134, P0154, use the hand-held tester to confirm the output voltage of the HO2S (bank 1 sensor 1 and bank 2 sensor 1). If the voltage output of the HO2S is less than 0.1 V, the HO2S circuit may be open or short.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Condition:
Typical Malfunction Thresholds:
The ECM uses the heated oxygen sensor to optimize the air-fuel mixture in the closed-loop fuel control.
This control helps decrease exhaust emissions by providing the catalyst with a nearly stoichiometric mixture.The sensor detects the oxygen level in the exhaust gas and the ECM uses this data to control the air-fuel ratio. The sensor output voltage ranges from 0 V to 1 V. If the signal voltage is less than 0.4 V, the air-fuel ratio is LEAN. If the signal voltage is more than 0.55 V, the air-fuel ratio is RICH. If the sensor does not indicate RICH even once despite the conditions for the closed-loop fuel control being met and a specified time period has passed, the ECM will conclude that the closed-loop fuel control is malfunctioning. The ECM will illuminate the Malfunction Indicator Light (MIL) and set a DTC.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
a. Connect the hand-held tester to the DLC3.
b. Switch from normal mode to the 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 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 - 4:
Step 5 - 7:
Step 8 - 13:
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 the 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.