Diagnostic Instructions
DTC Descriptor
DTC P0133: HO2S Slow Response Sensor 1
Circuit Description
The heated oxygen sensors (HO2S) are used for fuel control and catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the engine is started, the control module operates in an
Open Loop mode, ignoring the HO2S signal voltage while calculating the air-to-fuel ratio. The control module supplies the HO2S with a reference, or bias voltage of about 450 mV. While the engine runs, the HO2S heats up and begins to generate a voltage
within a range of 0-1,000 mV. This voltage will fluctuate above and below the bias voltage. Once sufficient HO2S voltage fluctuation is observed by the control module, Closed Loop is entered. The control module uses the HO2S voltage to determine
the air-to-fuel ratio. An HO2S voltage that increases above bias voltage toward 1,000 mV indicates a rich fuel mixture. An HO2S voltage that decreases below bias voltage toward 0 mV indicates a lean fuel mixture.
The heating elements inside each HO2S heat the sensor to bring the sensor up to operating conditions faster. This allows the system to enter Closed Loop earlier and the control module to calculate the air-to-fuel ratio sooner.
The HO2S utilizes the following circuits:
• | A low reference circuit |
• | An ignition 1 voltage circuit |
• | A heater control circuit |
Conditions for Running the DTC
• | DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0141, P0300, P0335, P0336, P0337, P0341, P0342, P0400, P0404, P0405, P0406, P0444, P0445, P0501, P1320, P1321, P1402, P1403, P1511, P1512, and P1513 are not set. |
• | The engine coolant temperature is more than 70°C (158°F). |
• | The evaporative emission (EVAP) purge solenoid pulse width modulation (PWM) is less than 100 percent. |
• | The fuel system is in Closed Loop. |
• | The engine speed is between 2,016-2,400 RPM. |
• | The vehicle speed is between 60-80 km/h (28-34 mph). |
• | The air flow into the engine is between 30-60 kg/h. |
• | The DTC runs once per ignition cycle when the above conditions are met for 2 seconds. |
Conditions for Setting the DTC
• | The ECM detects that the HO2S rich-to-lean average response time or lean-to-rich average response time is more than 3 times the normal transition time for 10-20 minutes depending on engine load and speed. |
• | The ECM detects that the HO2S signal spends more time in the rich region as compared to the lean region or the HO2S signal spends more time in the lean region as compared to the rich region for 10-20 minutes depending engine load and speed. |
Action Taken when the DTC Sets
DTC P0133 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P0133 is a Type B DTC.
Reference Information
Schematic Reference
Engine Controls Schematics
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Engine running, observe the DTC information with a scan tool. DTCs P0131, P0132, P0133, P0135, P0137, P0138, P0140, or P0141 should not set.
- Observe the DTC information with a scan tool. DTC P0133 should not set.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Verify none of the following conditions exist:
• | The HO2S is not securely installed. |
• | Water intrusion or corrosion in the HO2S harness connector |
• | Poor terminal tension at the HO2S and at the ECM |
• | HO2S wiring harness damage |
• | Fuel saturation of the EVAP canister |
⇒ | If you find any of the above conditions, repair as necessary. |
- If all conditions test normal, test or replace the appropriate HO2S.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine control module replacement, setup, and programming