Diagnostic Instructions
DTC Descriptor
DTC P1133: HO2S Insufficient Switching Bank 1
DTC P1153: HO2S Insufficient Switching Bank 2
Circuit/System Description
The heated oxygen sensors (HO2S) are used for fuel control. 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 P0068, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0220, P0222, P0223, P1516, P2101, P2119, or P2176 are not set |
| • | The engine coolant temperature is greater than 60°C (140°F) |
| • | The engine speed is between 1,200-3,000 RPM |
| • | The ignition 1 voltage is between 10-16 volts |
| • | The engine has been operating for greater than 160 seconds |
| • | The fuel system is in Closed Loop |
| • | The TP Indicated Angle is greater than 5 percent |
| • | The BARO Pressure is greater than 70 kPa (10 psi) |
| • | The calculated airflow into the engine is between 20-55 g/s |
| • | The DTC runs continuously when the above conditions are met for 2 seconds |
Conditions for Setting the DTC
The ECM detects that the HO2S rich-to-lean counts, or the lean-to-rich counts are less than a calibrated value.
Action Taken when the DTC Sets
DTCs P1133 and P1153 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P1133 and P1153 are Type B DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Engine Control Module Scan Tool Information
Circuit/System Verification
- Engine running, observe the DTC information with a scan tool. Verify that other DTCs are not set.
- Observe the DTC information with a scan tool. DTC P1133 or P1153 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:
| • | Water intrusion in the HO2S harness connector |
| • | HO2S wiring harness damage |
| • | Exhaust leaks near the HO2S |
| • | Engine coolant consumption |
| ⇒ | 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.
