Troubleshooting
DTC P0134 OXYGEN SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 1 SENSOR 1)CIRCUIT DESCRIPTION
DTC Detecting Condition:
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The heated oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. This is used to detect the oxygen concentration in the exhaust gas and to provide the ECM with feedback control the air-fuel ratio.
When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust gas increases. And the heated oxygen sensor informs the ECM of the LEAN condition (low voltage, i. e. less than 0.45 V). When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas is reduced. And the heated oxygen sensor informs the ECM of the RICH condition (high voltage, i. e. more than 0.45 V). The ECM judges whether the air-fuel ratio is RICH or LEAN by voltage from the heated oxygen sensor, and controls the injection timing accordingly. However, if the malfunction of the heated oxygen sensor causes abnormal voltage output, the ECM becomes unable to perform the accurate air-fuel ratio control.
The heated oxygen sensors include a heater which heats the zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), the current flows to the heater in order to heat the sensor for the accurate oxygen concentration detection.
HINT:
- Bank 1 refers to bank that includes cylinder No. 1.
- Bank 2 refers to bank that does not includes cylinder No. 1.
- Sensor 1 refers to the sensor farthest away from the engine body.
- After confirming DTCs P0134 and P0154, use the hand-held tester or the OBD II scan tool to confirm the output voltage of the heated oxygen sensor (bank 1, 2 sensor 1) from the DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL. If the output voltage of the heated oxygen sensor is less than 0.1 V, the heated oxygen sensor circuit may be open or short.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Condition:
Typical Malfunction Thresholds:
Component Operating Range:
The ECM uses the heated oxygen sensor to optimize the air-fuel mixture in 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 0.5 V, the air-fuel ratio is RICH. If the conditions for closed-loop fuel control are met and after a specified time period, the sensor's output signal never indicates RICH, the ECM will conclude that closed-loop fuel control is malfunctioning. The ECM will illuminate the MIL and a DTC is set.
Wiring Diagram:
Step 1 - 2:
Step 2 (continued) - 5:
Step 6 - 7:
Step 8 - 13:
Step 13(continued) - 14:
INSPECTION PROCEDURE
HINT:
Hand-held tester only: It is possible the malfunctioning area can be found using the ACTIVE TEST A/F CONTROL operation. The A/F CONTROL operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.
a. Perform the ACTIVE TEST A/F CONTROL operation.
HINT:
The A/F CONTROL operation lowers the injection volume 12.5% or increases the injection volume 25%.
1. Connect the hand-held tester to the DLC3 on the vehicle.
2. Turn the ignition switch to ON.
3. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
4. Select the item: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
5. Perform the A/F CONTROL operation with the engine in an idle condition (press the right or left button).
Result:
Heated oxygen sensor reacts in accordance with increase and decrease of injection volume:
+25 % -> rich output: More than 0.5 V
-12.5 % -> lean output: Less than 0.4 V
NOTE: There is a delay of few seconds in the sensor 1 (front sensor) output, and there is about 20 seconds delay at maximum in the sensor 2 (rear sensor).
The A/F CONTROL procedure enables the technician to check and graph the voltage outputs of both the heated oxygen sensor.
To display the graph, enter ACTIVE TEST/ A/F CONTROL/USER DATA, then select "O2S B1S1 and O2S B1S2" or "O2S B2S1 and O2S B2S2" 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 will be recorded, and the MIL then illuminates.
HINT:
- If different DTCs related to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may be open.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. 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.
- A high heated oxygen 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 heated oxygen 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.
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. Start the engine and let the engine idle.
d. Drive the vehicle at 40 km/h (25 mph) or more for 25 seconds or more.
e. Let the engine idle for 30 seconds or more. Perform steps (d) and (e) at least 3 times. (f) Let the engine idle for 30 seconds.
HINT: If malfunction exists, the CHK ENG will be illuminated during step (f).
NOTE: If the conditions in this test are not strictly followed, no malfunction will be detected.
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 (c) to (f) again.
CHECK FOR INTERMITTENT PROBLEMS
HINT:
Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in check mode with a hand-held tester. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default) using 2 trip detection logic.
a. Clear the DTCs.
b. Switch the hand-held tester from normal mode to check mode.
c. Perform a simulation test.
d. Check the connector(s) and terminal(s).
e. Wiggle the harness(s) and connector(s).