Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0133: HO2S Slow Response Sensor 1DTC P0139: HO2S Slow Response Sensor 2
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
HO2S Signal | P0131, P0137 | P0134, P0140 | P0132, P0138 | P0133, P0139 |
Low Reference | -- | P0134, P0140 | P0132, P0138 | P0133, P0139 |
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 signal circuit |
| • | A low reference circuit |
| • | An ignition 1 voltage circuit |
| • | A heater control circuit |
Conditions for Running the DTC
P0133
| • | DTCs P0031, P0032, P0037, P0038, P0106, P0107, P0108, P0110, P0111, P0112, P0113, P0116, P0117, P0118, P0122, P0123, P0135, P0141, P0171, P0172, P0201, P0202, P0203, P0204, P0217, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0313, P0335, P0336, P0337, P0351, P0352, P0401, P0402, P0404, P0405, P0406, P0443, P0458, P0459, P0488, P0496, P0502, P0506, P0507, P0562, P0563, P1166, P2110 and P2297 are not set. |
| • | The calculated airflow into the engine is between 9-40 g/s. |
| • | The engine speed is between 1,500-4,300 RPM. |
| • | The engine coolant temperature is greater than 70°C (158°F). |
| • | The ignition 1 voltage is greater than 10 volts. |
| • | The fuel system is in Closed Loop. |
| • | The evaporative emissions (EVAP) purge is less than 20 percent. |
| • | The engine has been operating for 60 seconds. |
| • | The vehicle is not decelerating. |
| • | Torque fuel reduction is not active. |
| • | The DTC runs continuously when the above conditions are met for 2 seconds. |
P0139
This DTC runs with DTC P0420.
Conditions for Setting the DTC
P0133
The ECM detects that the HO2S 1 rich-to-lean or lean-to-rich counts are less than 60 counts.
P0139
The ECM detects that the HO2S 2 response time is greater than 25 seconds after DTC P0420 runs.
Action Taken when the DTC Sets
DTC P0133 and P0139 are Type B DTCs.
DTC P0133
The ECM commands open loop fuel control.
Conditions for Clearing the MIL/DTC
DTC P0133 and P0139 are Type B DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Ignition ON, observe the scan tool MAP sensor pressure parameter. Start the engine, verify the scan tool MAP sensor pressure parameter changes.
- Verify that other DTCs are not set.
- Operate the vehicle within the conditions for running the DTC. DTC P0133 or P0139 should not set.
- If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Important: In extreme cold weather conditions ice may form in the vacuum source to the MAP sensor and may set a DTC. Inspect the MAP sensor and the vacuum source for ice, moisture, or other restrictions.
| ⇒ | If the scan tool MAP sensor pressure parameter does not change, refer to DTC P0107 or P0108 for further diagnosis. |
| ⇒ | If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
- Verify that none of the following conditions exist:
- If all conditions test normal, replace the appropriate HO2S.
| • | Lean or rich fuel injectors--Refer to Fuel Injector Balance Test with Special Tool . |
| • | Water intrusion in the HO2S harness connector |
| • | HO2S wiring harness damage |
| • | Incorrect RTV sealant |
| • | Low or high fuel system pressure--Refer to Fuel System Diagnosis . |
| • | Fuel that is contaminated--Refer to Alcohol/Contaminants-in-Fuel Diagnosis . |
| • | Fuel saturation of the evaporative emission (EVAP) canister |
| • | Exhaust leaks near the HO2S |
| • | Engine vacuum leaks |
| • | Engine oil consumption--Refer to Oil Consumption Diagnosis . |
| • | Engine coolant consumption--Refer to Loss of Coolant |
| ⇒ | If you find any of the above conditions, repair as necessary. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
