Toyota
Yaris NCP90 91 92 93
Repair Manual
1Nz-Fe Engine Control System
Sfi System
DTC P0133 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 1)
- HINT:
- Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.
DESCRIPTION
Refer to DTC P0130 (Click here).| DTC No. | DTC Detection Conditions | Trouble Areas |
| P0133 | While idling with warm engine, response time for voltage output of Heated Oxygen (HO2) sensor to change from rich to lean or from lean to rich is 1 second or more (2 trip detection logic) |
|
WIRING DIAGRAM
Refer to DTC P0130 (Click here).CONFIRMATION DRIVING PATTERN

- HINT:
- This confirmation driving pattern is used in the "PERFORM CONFIRMATION DRIVING PATTERN" procedure of the following diagnostic troubleshooting procedure.
- (1) Connect an intelligent tester to the DLC3.
- (2) Turn the ignition switch to ON and turn the tester on.
- (3) Clear DTCs (Click here).
- (4) Switch the ECM from normal mode to check mode (Click here).
- (5) Start the engine.
- (6) Allow the engine to idle until the engine coolant temperature reaches 40°C (104°F).
- (7) Drive the vehicle at a vehicle 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 (7) and (8) described above at least 3 times.
- (10) Allow the engine to idle for 40 seconds or more.
- HINT:
- The MIL is illuminated during step (10) if a malfunction still exists.
- NOTICE:
- If the conditions in this test are not strictly followed, malfunctions may not be detected.
INSPECTION PROCEDURE
- HINT:
- It is possible that the malfunctioning area can be found using the Active Test Control operation. The Active Test can determine if the heated oxygen sensor or other potential trouble areas are malfunctioning or not.
- The injection volume can be switched to -12.5% (decrease) or +25% (increase) by the Active Test.
- The Active Test procedure enables a technician to check and graph the voltage outputs of the heated oxygen sensors.
- Procedure:
- Connect an intelligent tester to the DLC3.
- Turn the ignition switch to ON.
- Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
- Select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
- Perform the Active Test while the engine is idling.
- Connect an intelligent tester to the DLC3.
- Standard:
- The heated oxygen sensor reacts in accordance with the increases and decreases in injection volume:
+25% → RICH output: More than 0.5 V
-12.5% → LEAN output: Less than 0.4 V
- NOTICE:
- The heated oxygen sensor (sensor 1) has an output delay of a few seconds and the heated oxygen sensor (sensor 2) has a maximum output delay of 20 seconds.
- If the vehicle is short of fuel, the air-fuel ratio becomes LEAN and the DTCs are recorded.
| Case | Heated Oxygen Sensor (Sensor 1) Output Voltage | Heated Oxygen Sensor (Sensor 2) Output Voltage | Main Suspected Trouble Area |
| 1 | ![]() ![]() | ![]() ![]() | - |
| 2 | ![]() ![]() | ![]() ![]() |
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| 3 | ![]() ![]() | ![]() ![]() |
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| 4 | ![]() ![]() | ![]() ![]() |
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- HINT:
- Read freeze frame data using the intelligent 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.
Connect an intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Select the following menu items: Powertrain / Engine and ECT / DTC.
Read DTCs.
- Result:
Display (DTC Output) Proceed To P0133 A P0133 and other DTCs B
- HINT:
- If any DTCs other than P0133 are output, troubleshoot those DTCs first.
| GO TO DTC CHART (Click here) | |||
| A | |
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Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Start the engine.
Select the following menu items: Powertrain / Engine and ECT / Data List / O2S B1S1.
Warm up the Heated Oxygen (HO2) sensor at an engine speed of 2,500 rpm for approximately 90 seconds.
Read the voltage output of the front HO2 sensor displayed on the tester, while the engine is idling.
- Standard:
- Fluctuates between less than 0.4 V and more than 0.5 V, and period "t" is less than 1 second (refer to table below).

| Go to step 9 | |||
| NG | |
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Disconnect the C36 HO2 sensor (sensor 1) connector.
Check the resistance.
- Standard resistance:
Tester Connections Specified Conditions HT1A (1) - +B (2) 5.3 to 7.5 Ω at 20 °C (68°F) HT1A (1) - E2 (4) 10 kΩ or higher
Reconnect the HO2 sensor connector.
| REPLACE HEATED OXYGEN SENSOR | |||
| OK | |
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Remove the integration relay from the engine room relay block.
Inspect the EFI fuse.
Remove the EFI fuse from the integration relay.
Check the EFI fuse resistance.
- Standard resistance:
- Below 1 Ω
Reinstall the EFI fuse.
Inspect the EFI relay.
Check the EFI relay resistance.
- Standard resistance:
Tester Connections Specified Conditions 1C-1 - 1A-4 10 kΩ or higher Below 1 Ω
(Apply battery voltage between terminals 1A-2 and 1A-3)
Reinstall the integration relay.
| REPLACE INTEGRATION NO.1 RELAY | |||
| OK | |
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Disconnect the C36 HO2 sensor (sensor 1) connector.
Disconnect the C20 ECM connector.
Check the resistance.
- Standard resistance (Check for open):
Tester Connections Specified Conditions OX1A (C36-3) - OX1A (C20-112) Below 1 Ω HT1A (C36-1) - HT1A (C20-109)
- Standard resistance (Check for short):
Tester Connections Specified Conditions OX1A (C36-3) or OX1A (C20-112) - Body ground 10 kΩ or higher HT1A (C36-1) or HT1A (C20-109) - Body ground
Reconnect the HO2 sensor connector.
Reconnect the ECM connector.
| REPAIR OR REPLACE HARNESS OR CONNECTOR | |||
| OK | |
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Check the air induction system for vacuum leaks.
- OK:
- No leakage from air induction system.
| REPAIR OR REPLACE AIR INDUCTION SYSTEM | |||
| OK | |
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Check the fuel pressure (Click here).
| REPAIR OR REPLACE FUEL SYSTEM | |||
| OK | |
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Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor).
| REPLACE FUEL INJECTOR (Click here) | |||
| OK | |
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| REPLACE HEATED OXYGEN SENSOR (Click here) | |
- HINT:
- Clear all DTCs before performing the confirmation driving pattern.
| NEXT | |
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Connect an intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Select the following menu items: Powertrain / Engine and ECT / DTC.
Read DTCs.
- Result:
Display (DTC Output) Proceed To P0133 A No output B
| CHECK FOR INTERMITTENT PROBLEMS (Click here) | |||
| A | |
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| REPLACE HEATED OXYGEN SENSOR (Click here) | |











