P0133
DTC P0133 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 1)DESCRIPTION
DTC Detection Condition:
The Heated Oxygen (HO2) sensor (bank 1 sensor 1) monitors the oxygen concentration in the exhaust gas. For optimum TWC operation, the air-fuel mixture must be maintained as close as possible to the stoichiometric ratio. The HO2 sensor output voltage changes dramatically in the vicinity of the stoichiometric ratio. By making adjustments in accordance with these signal voltages, the ECM adjusts the fuel injection time so that the air-fuel ratio remains close to stoichiometric levels.
If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is lean and the HO2 sensor output voltage to the ECM drops below 0.45 V. If the oxygen concentration in the exhaust gas decreases, the air-fuel ratio is rich and the HO2 sensor output voltage to the ECM increases to above 0.45 V.
HINT: Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions (Part 1):
Typical Enabling Conditions (Part 2):
Typical Malfunction Thresholds:
Component Operating Range:
The Heated Oxygen (HO2) sensor detects the oxygen levels in the exhaust gas and transmits this information to the ECM, which uses it to maintain the air-fuel ratio as close as possible to stoichiometric levels. This optimizes the three-way catalytic converter's ability to purify the exhaust gases. The sensor element is made of platinum electrode and solid electrolyte (zirconia element), and includes an integrated heating element. The inner surface of the sensor element is exposed to the outside air and the outer surface is exposed to the exhaust gases.
The HO2 sensor generates a waveform voltage signal that oscillates between 0.1 V and 0.9 V in accordance with the oxygen concentration in the exhaust gas. The HO2 sensor has a characteristic whereby this output voltage changes dramatically in the vicinity of the stoichiometric air-fuel ratio. When the output voltage of the HO2 sensor is 0.55 V or more, the ECM determines that the air-fuel ratio is rich. When it is 0.40 V or less, the ECM determines that the air-fuel ratio is lean.
The ECM also monitors the response of the HO2 sensor. If the response time of the output changes from rich to lean or vice versa becomes longer than preset thresholds, the ECM interprets this as a malfunction in the HO2 sensor, illuminates the MIL and sets the DTC (2 trip detection logic).
MONITOR RESULT
Refer to detailed information. Mode 6 Data
CONFIRMATION DRIVING PATTERN
HINT: This confirmation driving pattern is used in the "PERFORM CONFIRMATION DRIVING PATTERN" procedure of the following diagnostic troubleshooting procedure.
Confirmation Driving Pattern:
1. Connect the intelligent tester to the DLC3.
2. Turn the ignition switch ON and turn the tester ON.
3. Clear DTCs.
4. If using the intelligent tester, switch the ECM from normal mode to check mode.
5. Start the engine.
6. Allow the engine to idle until the engine coolant temperature reaches 75 degrees C (167 degrees F).
7. Drive the vehicle at an engine speed of more than 40 km/h (25 mph) for 35 seconds or more.
8. Allow the engine to idle for 40 seconds or more.
9. Repeat steps 6. and (7) described above at least 3 times.
10. Allow the engine to idle for 40 seconds or more.
HINT: When using the intelligent tester: The MIL will be illuminated during step (10) if a malfunction still exists.
CAUTION: If the conditions in this test are not strictly followed, malfunctions may not be detected.
HINT: Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Heated Oxygen (HO2) sensors and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using the intelligent tester.
1. Connect the intelligent tester to the DLC3.
2. Start the engine and turn the tester ON.
3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
4. Enter the following menus: 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 to change the fuel injection volume).
6. Monitor the voltage output of the HO2 sensors (O2S B1S1 and O2S B1S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
NOTE: The front HO2 sensor has an output delay of a few seconds and the rear HO2 sensor has a maximum output delay of approximately 20 seconds.
- Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the front and rear HO2 sensors.
- To display the graph, enter the following menus on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST/ A/F CONTROL / USER DATA / O2S B1S1 and O2S B1S2; then press the YES button and ENTER button followed by the F4 button.
Wiring Diagram:
Step 1-2:
Step 2(Continued)-4:
Step 5:
Step 5(Continued)-10:
Step 10(Continued):
INSPECTION PROCEDURE
NOTE: If the vehicle is short of fuel, the air-fuel ratio becomes lean and HO2 sensor DTCs are recorded, and the ECM illuminates the MIL.
HINT:
- If other DTCs relating 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 intelligent tester. Freeze frame data records 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.