P0134
DTC P0134 Oxygen Sensor Circuit No Activity Detected (Bank 1 Sensor 1)CIRCUIT DESCRIPTION
DTC Detecting 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: After confirming DTC "P0134", use the hand-held tester or the OBD II scan tool to confirm the output voltage of the heated oxygen sensor (bank 1 sensor 1) from the "DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL". If the output voltage of the heated oxygen sensor is always less than 0.1 V, the heated oxygen sensor circuit may be open or short.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
Component Operating Range:
The ECM uses the Heated Oxygen (HO2) sensor to optimize the air-fuel mixture with closed-loop fuel control. This control helps to decrease exhaust emissions by supplying 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 closed-loop fuel control being met and a specified time period has passed, the ECM concludes that closed-loop fuel control is malfunctioning. The ECM illuminates the MIL and sets the DTC.
Wiring Diagram:
CONFIRMATION DRIVING PATTERN
Confirmation Driving Pattern:
a. Connect the hand-held tester to the DLC3.
b. Allow the engine to idle until engine coolant temperature reaches 40 °C (104 °F).
c. Allow the vehicle to run at 60 km/h (38 mph) or more for 3 minutes or more.
INSPECTION PROCEDURE
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:
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 (HO2) sensors.
To display the graph, enter ACTIVE TEST/A/F CONTROL / USER DATA, select "02S 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.
Step 1 - 2:
Step 3 - 5:
Step 6:
Step 7 - 10:
Step 11 - 14:
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 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).